This PR updates mimic to support multi-eef (DexMimicgen) data
generation.
It consists of the following major changes:
- Updated mimic code to support environments with multiple end effectors
- Added support for setting subtask constraints based on DexMimicGen
- Updated annotate_demos.py to support annotating subtask term signals
for multiple end effectors
- Updated mimic API target_eef_pose_to_action() to take noise as
dictionary of eef noise values instead of a single value

- New feature (non-breaking change which adds functionality)
- Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- This change requires a documentation update

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) 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
- [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