Added a stochastic action wrapper along with its test

[BolunDai0216]

Description

This PR adds a new wrapper that makes the action stochastic. In the wrapper, the user can specify the probability that a random action is applied, along with what kind of random action is applied (it can either be a truly random action sampled from the action space or a user-specified action).

Type of change

• New feature (non-breaking change which adds functionality)

Checklist:

• I have run the pre-commit checks with pre-commit run --all-files (see CONTRIBUTING.md instructions to set it up)
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• 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

[pseudo-rnd-thoughts]

@BolunDai0216 Why should we add this as a random action in minigrid rather than gymnasium?

[BolunDai0216]

@BolunDai0216 Why should we add this as a random action in minigrid rather than gymnasium?

It is to make the library more complete. Additionally, in the future, we can update the wrapper to specifically handle random action needs in Miniworld instead. If it is in gymnasium, it would need to be more general such that it is applicable to all gymnasium related libraries.

[pseudo-rnd-thoughts]

We can include this in minigrid and move it to gymnasium later if we think that it is important