MuJoCo Simulator

[kdelmo1]

Description

This PR adds support for the MuJoCo physics engine to Scenic. It introduces a new simulator interface, a modular robot model, and procedural terrain generation.

Key Contributions:

• New Simulator: Added scenic.simulators.mujoco to interface with the MuJoCo physics engine.
• Robot Model: Implemented the Farm-ng Amiga agricultural robot with torque-controlled wheels and modular components.
• Procedural Environments: Added support for generating irregular terrain (hills) and crop rows.
• Tests: Added tests/simulators/mujoco/test_mujoco.py covering ground generation, terrain, and full robot integration (headless).
• Dependency Fix: Pinned antlr4-python3-runtime==4.9.3 to resolve a version conflict with Hydra/Omegaconf.

Issue Link

N/A (New Feature)

Checklist

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.63%. Comparing base (156b54b) to head (211b9c5).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #433      +/-   ##
==========================================
- Coverage   90.01%   89.63%   -0.38%     
==========================================
  Files          54       48       -6     
  Lines       13585    13190     -395     
==========================================
- Hits        12228    11823     -405     
- Misses       1357     1367      +10     

see 54 files with indirect coverage changes

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