Refactor build and experiments runner

[alantrrs]

Hard requirements

• [x] Build multiple images
• [x] Be able to launch multiple experiments per build

  TBD

Separate into:

• [ ] Build worker
• [ ] Experiments worker

[alantrrs]

Definitely NOT separate into build worker and experiment worker. Building is a dependency of running + the image must be in the same host where the experiment will run. Other refactors are going into: https://github.com/alantrrs/emp/issues/6