Add reset_target argument to antmaze environments

[rodrigodelazcano]

Description

This PR adds the reset_target boolean argument to v4 antmaze environments. If this argument is set to True and continuing_task is also True, the goal won't be re-generated to another location when reached by the agent. If False and continuing_task still equals True, then another goal location will be generated instead of terminating/truncating the episode when the ant reaches a goal.

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 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 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