Prepare for OpenDC 2.0 release (v1)

This pull request performs several preparations for the official release of OpenDC 2.0. 
This pull request mostly focuses on documentation changes.

## Details
1. Restructure project documentation
2. Migrate to Dokka 1.4.32
3. Merge CI builds into single workflow

9 files changed, 195 insertions, 0 deletions

diff --git a/docs/architecture.md b/docs/architecture.md
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+# Architecture
+
+OpenDC consists of four components: a Kotlin simulator, a MongoDB database, a Python
+Flask [API](/opendc-web/opendc-web-api), and a React.js [frontend](/opendc-web/opendc-web-ui).
+
+<p align="center">
+    <img src="https://raw.githubusercontent.com/atlarge-research/opendc/master/misc/artwork/opendc-component-diagram.png" alt="OpenDC Component Diagram">
+</p>
+
+On the frontend, users can construct a topology by specifying a datacenter's rooms, racks and machines, and create
+scenarios to see how a workload trace runs on that topology. The frontend communicates with the web server over
+SocketIO, through a custom REST request/response layer. For example, the frontend might make a `GET` request
+to `/api/v1/users/{userId}`, but this request is completed via SocketIO, not plain HTTP requests. Note that the API
+itself can also be accessed by HTTP.
+
+The (Swagger/OpenAPI compliant) API spec specifies what requests the frontend can make to the web server. To view this
+specification, go to the [Swagger Editor](https://editor.swagger.io/) and paste in
+our [opendc-api-spec.yml](../opendc-api-spec.yml).
+
+The web server receives API requests and processes them in the database. When the frontend requests to run a new
+scenario, the web server adds it to the `scenarios` collection in the database and sets its `state` as `QUEUED`.
+
+The simulator monitors the database for `QUEUED` scenarios, and simulates them as they are submitted. The results of the
+simulations are processed and aggregated in memory. Afterwards, the aggregated summary is written to the database, which
+the frontend can then again retrieve via the web server.
diff --git a/docs/deploy.md b/docs/deploy.md
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+# Deploying OpenDC
+
+### Preamble
+
+The official way to run OpenDC is using Docker. Other options include building and running locally, and building and
+running to deploy on a server.
+
+For all of these options, you have to create a Google API Console project and client ID, which the OpenDC frontend and
+web server will use to authenticate users and requests.
+Follow [these steps](https://developers.google.com/identity/sign-in/web/sign-in) to make such a project. In the '
+Authorized JavaScript origins' and 'Authorized redirect URI' fields, be sure to add `http://localhost:8080` (frontend)
+, `http://localhost:8081` (api) and `https://localhost:3000` (frontend dev). Download the JSON of the OAuth 2.0 client
+ID you created from the Credentials tab, and specifically note the `client_id`, which you'll need to build OpenDC.
+
+### Installing Docker
+
+OpenDC uses [Docker](https://www.docker.com/) and [Docker Compose](https://docs.docker.com/compose/) to orchestrate the
+deployment of the software stack. Please refer to [Docker Desktop](https://www.docker.com/products/docker-desktop) for
+instructions on how install Docker on your machine.
+
+### Running OpenDC
+
+To build and run the full OpenDC stack locally on Linux or Mac, you first need to clone the project:
+
+```bash
+git clone https://github.com/atlarge-research/opendc.git
+
+# Enter the directory
+cd opendc/
+```
+
+In the directory you just entered, you need to set up a set of environment variables. To do this, create a file
+called `.env` in the `opendc` folder. In this file, replace `your-google-oauth-client-id` with your `client_id` from the
+OAuth client ID you created. For a standard setup, you can leave the other settings as-is.
+
+```.env
+MONGO_INITDB_ROOT_USERNAME=root
+MONGO_INITDB_ROOT_PASSWORD=rootpassword
+MONGO_INITDB_DATABASE=admin
+OPENDC_DB=opendc
+OPENDC_DB_USERNAME=opendc
+OPENDC_DB_PASSWORD=opendcpassword
+OPENDC_FLASK_SECRET="This is a secret flask key, please change"
+OPENDC_OAUTH_CLIENT_ID=your-google-oauth-client-id
+OPENDC_API_BASE_URL=http://localhost:8081
+```
+
+We provide a list of default traces for you to experiment with. If you want to add others, place them in the `traces`
+directory and add entries to the database (see also [the database folder](database/mongo-init-opendc-db.sh))
+
+If you plan to publicly deploy, please also tweak the other settings. In that case, also check the `docker-compose.yml`
+and `docker-compose.pod.yml` for further instructions.
+
+Now, start the server:
+
+```bash
+# Build the Docker image
+docker-compose build
+
+# Start the containers
+docker-compose up
+```
+
+Wait a few seconds and open `http://localhost:8080` in your browser to use OpenDC. We recommend Google Chrome for the
+best development experience.
diff --git a/docs/images/logo.png b/docs/images/logo.png
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diff --git a/docs/images/opendc-component-diagram.png b/docs/images/opendc-component-diagram.png
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diff --git a/docs/images/opendc-frontend-construction.png b/docs/images/opendc-frontend-construction.png
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diff --git a/docs/images/opendc-frontend-simulation-zoom.png b/docs/images/opendc-frontend-simulation-zoom.png
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diff --git a/docs/images/opendc-frontend-simulation.png b/docs/images/opendc-frontend-simulation.png
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diff --git a/docs/research.md b/docs/research.md
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+## Research with OpenDC
+
+This document contains publications related to OpenDC or publications that have used OpenDC in their work.
+
+## Publications about OpenDC
+
+1. [OpenDC 2.0: Convenient Modeling and Simulation of Emerging Technologies in Cloud Datacenters](https://atlarge-research.com/pdfs/ccgrid21-opendc-paper.pdf)  
+   **CCGrid 2021**  
+   Fabian Mastenbroek, Georgios Andreadis, Soufiane Jounaid, Wenchen Lai, Jacob Burley, Jaro Bosch, Erwin van Eyk,
+   Laurens Versluis, Vincent van Beek, Alexandru Iosup
+1. [The OpenDC vision: Towards collaborative datacenter simulation and exploration for everybody](https://atlarge-research.com/pdfs/opendc-vision17ispdc_cr.pdf)  
+   **ISPDC 2017 (invited paper)**  
+   Alexandru Iosup, Georgios Andreadis, Vincent van Beek, Matthijs Bijman, Erwin van Eyk, Mihai Neacsu, Leon Overweel,
+   Sacheendra Talluri, Laurens Versluis, Maaike Visser.
+
+## Publications using OpenDC
+
+1. [A Reference Architecture for Datacenter Scheduling](https://arxiv.org/pdf/1808.04224)   
+   **International Conference for High Performance Computing, Networking, Storage and Analysis 2018 (SC18)**   
+   Georgios Andreadis, Laurens Versluis, Fabian S. Mastenbroek, Alexandru Iosup
+
+## Students using OpenDC
+
+1. [Capelin: Fast Data-Driven Capacity Planning for Cloud Datacenters](https://repository.tudelft.nl/islandora/object/uuid:d6d50861-86a3-4dd3-a13f-42d84db7af66?collection=education)  
+   **Master Thesis, 2020**  
+   Georgios Andreadis
+1. [OpenDC Serverless: Design, Implementation and Evaluation of a FaaS Platform Simulator](https://zenodo.org/record/4046675)  
+   **Bachelor Thesis, 2020**  
+   Soufiane Jounaid
+1. LEGO, but with Servers: Creating the Building Blocks to Design and Simulate Datacenters  
+   **Bachelor Thesis, 2020**  
+   Jacob Burley
+1. [A Systematic Design Space Exploration of Datacenter Schedulers](https://repository.tudelft.nl/islandora/object/uuid%3A20478016-cc7d-4c87-aa12-25b46f511277?collection=education)  
+   **Bachelor Thesis, 2019**  
+   Fabian S. Mastenbroek
diff --git a/docs/toolchain.md b/docs/toolchain.md
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+# Toolchain Setup
+
+The OpenDC simulator is built using the [Kotlin](https://kotlinlang.org/) language. This is a JVM-based language that
+should appear familiar to programmers knowledgeable in Java or Scala. For a short interactive introduction to Kotlin,
+the [Learn Kotlin By Example](https://play.kotlinlang.org/byExample/overview) docs are a great place to start.
+
+For the build and dependency toolchain, we use [Gradle](https://gradle.org/). You will likely not need to change the
+Gradle build configurations of components, but you will use Gradle to execute builds and tests on the codebase.
+
+Follow the steps below to get it all set up!
+
+## Contents
+
+1. [Installing Java](#1-installing-java)
+1. [Building and Developing](#2-building-and-developing)  
+    1. [Setup with IntelliJ IDEA](#21-setup-with-intellij-idea)
+    1. [Setup with Command Line](#22-setup-with-command-line)
+
+## 1. Installing Java
+
+Kotlin requires a Java installation of version 8 or higher. Make sure to install
+the [JDK](https://www.oracle.com/technetwork/java/javase/downloads/index.html), not only the JRE (the JDK also includes
+a JRE).
+
+## 2. Building and Developing
+
+With Java installed, we're ready to set up the development environment on your machine. You can either use a visual IDE
+or work from a command line shell. We outline both approaches below, feel free to choose which you are most comfortable
+with. If in doubt which one to choose, we suggest going with the first one.
+
+## 2.1 Setup with IntelliJ IDEA
+
+We suggest using [IntelliJ IDEA](https://www.jetbrains.com/idea/) as development environment. Once you have installed
+any version of this IDE on your machine, choose "Get from Version Control" in the new project dialogue.
+Enter `https://github.com/atlarge-research/opendc` as URL and submit your credentials when asked.
+Open the project once it's ready fetching the codebase, and let it set up with the defaults (IntelliJ will recognize
+that this is a Gradle codebase).
+
+You will now be prompted in a dialogue to enable auto-import for Gradle, which we suggest you do. Wait for any progress
+bars in the lower bar to disappear and then look for the Gradle context menu on the right-hand side. In it, go
+to `opendc > Tasks > verification > test`. This will build the codebase and run checks to verify that tests
+pass. If you get a `BUILD SUCCESSFUL` message, you're ready to go to the [next section](architecture.md)!
+
+## 2.2 Setup with Command Line
+
+First, clone the repository with the following command:
+
+```shell script
+git clone https://github.com/atlarge-research/opendc
+```
+
+And enter the directory:
+
+```shell script
+cd opendc
+```
+
+If on Windows, run the batch file included in the root, as follows:
+
+```commandline
+gradlew.bat test
+```
+
+If on Linux/macOS, run the shell script included in the root, as follows:
+
+```shell script
+./gradlew test
+```
+
+If the build is successful, you are ready to go to the next section!