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 change splits the opendc-compute module into two modules:

  1. opendc-compute-core
     The interfaces and APIs that represent a IaaS platform.
  2. opendc-compute-simulator
     The implementation of these interfaces using simulation components
     from opendc-simulator-compute.

This change creates an implementation of the BareMetalDriver interface
using the simulation logic of SimMachine. This implementation will
eventually replace the SimpleBareMetalDriver implementation.

This change adds an opendc-simulator-compute module which contains
interfaces related to simulating compute workloads. For future changes,
we intend to decouple the simulation part from the opendc-compute
module.

This change moves the OpenDC modules previously living in the simulator/opendc
directory to the simulator directory itself given that we do not make a
distinction between OpenDC and odcsim anymore.