Optional deps in using LeRobot as am optional package

[xyao-nv]

Hi, we are working on enabling LeRobot dataset generation in IsaacLab, such that developers could create data with IsaacLab data generation workflow and use it in their robot learning models.

The asks are,

1. Is there any scheduled release, such that downstream devs could have stable codebase to integrate LeRobot into their applications?
2. Can we move some deps as optional wrt the core code, if training/eval is not expected? For example, we only need Lerobot dataset related functions, Gymnasium dependency is not needed. You only need Gymnasium dependency if you want to use the environment in eval mode during training or deployment.

I hope those could expand the user base further for LeRobot dataset generation and for training/eval with broader model families.