Add multi-episode wrapper for AEC and parallel envs

[jjshoots]

Description

Requested by @elliottower. This basically allows the wrapping of either an AEC or Parallel env into an environment which runs for multiple episodes before truncating.

When there are no more valid agents in the underlying environment, the environment is automatically reset.
When this happens, the observation and info returned by step() are replaced with that of the reset environment.
The result of this wrapper is that the environment is no longer Markovian around the environment reset.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Checklist:

• I have run the pre-commit checks with pre-commit run --all-files (see CONTRIBUTING.md instructions to set it up)
• I have run pytest -v and no errors are present.
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I solved any possible warnings that pytest -v has generated that are related to my code to the best of my knowledge.
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[elliottower]

Looks good upon first glance will have to go through again in more detail later though

[elliottower]

Going to merge this as it’s a helpful utility on its own, though we are going to try to make a poker change that lets the chips persist for multiple hands which is an alternative to this.