Feature/actions as obs

[michele-milesi]

Summary

Describe the purpose of the pull request, including:

• Add ActionsAsObservationWrapper. The wrapper takes in input the number of the last actions to add to the observations and the dilation to use. It works as the FrameStack wrapper.
• Diambra environments do not use this wrapper, the library already provides a wrapper for adding the last n actions to the observations.

Type of Change

Please select the one relevant option below:

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

Checklist

Please confirm that the following tasks have been completed:

• I have tested my changes locally and they work as expected. (Please describe the tests you performed.)
• I have added unit tests for my changes, or updated existing tests if necessary.
• I have updated the documentation, if applicable.
• I have installed pre-commit and run locally for my code changes.