# Description

Sometimes users want to import a USD file which doesn't have any
collider meshes. This MR allows having such USD files in the terrain
importer for visualization purposes.

Additionally, the MR removes the storage of warp and tri-mesh based
meshes inside the class. These are stored into the USD and are read
directly from there whenever needed. Their intended use-case for having
them inside the terrain class is not needed.

## Type of change

- Bug fix (non-breaking change which fixes an issue)
- Breaking change

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [ ] 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

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Signed-off-by: Mayank Mittal <12863862+Mayankm96@users.noreply.github.com>
Co-authored-by: Kelly Guo <kellyguo123@hotmail.com>