Implement missing driving domain actions in MetaDrive interface

[lola831]

Description

Implements the missing driving domain actions in the MetaDrive interface (SetPositionAction, SetVelocityAction, SetHandBrakeAction, SetReverseAction) and makes control inputs persist until changed (as Scenic intends).

Issue Link

Issue 386

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.94%. Comparing base (d76f367) to head (827e79b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #387      +/-   ##
==========================================
+ Coverage   89.90%   89.94%   +0.03%     
==========================================
  Files          54       54              
  Lines       13560    13562       +2     
==========================================
+ Hits        12191    12198       +7     
+ Misses       1369     1364       -5     

Files with missing lines	Coverage Δ
src/scenic/domains/driving/actions.py	84.80% <ø> (+1.59%)	⬆️

... and 6 files with indirect coverage changes

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[dfremont]

Looks good, just a couple minor comments.

[dfremont]

Looks good, thanks Lola!