Add testing for step api compatibility functions and wrapper

[pseudo-rnd-thoughts]

Issue #3021 noted an issue with the step api compatibility.
Investigating, I found that there was no full testing for the functions.
This PR adds testing with expected values and roundtripping for both conversion functions.

Using is_vector_env works for both dict and list based info

Changes

• For the old done step api, in all cases where termination or truncation is true then "TimeLimit.truncation" is added to info
• As the old done step api can only encode 3 termination and truncation states (we cannot include terminated=True and truncated=True), in cases where terminated=True and truncated=True, we favour terminated=True and set truncated=False.

[arjun-kg]

Thank you especially for the super detailed test functions. Looks good except for some minor comments.

[arjun-kg]

Also in step_api_compatibility.py inside utils, the function names haven't been updated, which seems to be what CI is complaining about.

[vwxyzjn]

Thank you! I tested on my end, and the scripts run.