Centralize a bunch of boilerplate code in shared [environment / actor / sample producer] session

[cloderic]

Objective

• Limit the amount of repeated boilerplate codes
• Make it easy to support properly the patterns (for now teacher / student with action overrides but could be easily extended to further patterns)

Proposal

• Integrate all of this boilerplate in helpers that are mixed in at runtime in the session objects.

For now I've implemented it with the BC tutorial and gym once reviewed and validated we can generalize

[wduguay-air]

Update

• Finished the refactoring of all actors.
• Reworked the simple_bc tutorial documentation to reflect the changes
• Finished refactoring the remaining environment implementations (isaac_gym and overcooked)
• Fixed implementation of SAC Actor. It was missing some stuff from the migration to model_registry_v2
• Added a testing feature to test all hydra config compositions before testing the full cogment functional test runs.

@saikrishna-1996 I was not able to test our isaac_gym implementation of the ant environment with this refactoring. From our doc, I was not able to install isaac_gym. I think there may have been some changes on Nvidia side since its implementation in cogment-verse.