Add Manager-Based Environment for BD-X Locomotion Task

[louislelay]

Description

This PR introduces a new manager-based environment for the BD-X locomotion task. The BD-X USD file, along with its source, licensing details, and modifications, is available in this repository: Disney-BDX-USD-Description, as required by the IsaacLab contribution guidelines.

For debugging purposes, the configuration file currently imports the asset locally, following the recommendation outlined here, until the asset is uploaded to the Nucleus server. However, I did not include the asset in the data directory, as it is ignored by .gitignore, and I preferred not to override this setting. If necessary, I can add it.

Additionally, I have updated the environment list in the documentation.

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

Screenshots

rl-video-step-22000.mp4

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• 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
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[zoctipus]

This is so cute!