Description

Enhance base_height_l2 function to support rough terrain adjustments:

• Added an optional sensor_cfg parameter to allow dynamic target height
  adjustments based on sensor readings (e.g., RayCaster).
• Updated the function to calculate the L2 squared penalty using adjusted
  height values for rough terrain scenarios.
• Preserved existing behavior for flat terrain by using the fixed target_height.
• Improved compatibility for applications involving uneven terrain.

Fixes #1524

Type of change

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

Checklist

• [x ] I have run the pre-commit checks with ./isaaclab.sh --format
• [x ] I have made corresponding changes to the documentation
• [x ] My changes generate no new warnings
• [x ] I have added tests that prove my fix is effective or that my feature works
• [x ] I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• [x ] I have added my name to the CONTRIBUTORS.md or my name already exists there