This change updates the project structure to become flattened.
Previously, the simulator, frontend and API each lived into their own
directory.

With this change, all modules of the project live in the top-level
directory of the repository. This should improve discoverability of
modules of the project.

This pull request updates the Kotlin project to build with Gradle 7.0. 
This is necessary to support building the project with Java 16.

This change integrates the OpenTelemetry Metrics API in the OpenDC
Compute Service implementation. This replaces the old infrastructure for
gathering metrics.

This change updates the dependencies for the OpenDC simulator.

This commit implements the energy models that are present in CloudSim:
1. Constant
2. Linear
3. Cubic
4. Square root
5. Interpolation based on data.

This change updates the Gradle configuration to utilize version
constraints to force the same dependency version across modules.

This change moves the version of the dependencies from buildSrc to
gradle.properties to prevent recompilation when changing dependency
versions.