This change fixes various issues with the unit tests due to updates in
Isaac Sim and Kit builds. Notably, some extensions were renamed for the
URDF and MJCF importers, including minor modifications of available
parameters for the importers. The SimulationContext context will also
now terminate the process on exit due to the simulation stop callback
being triggered. We now bypass the callback for the unit tests.

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- Bug fix (non-breaking change which fixes an issue)
- Breaking change (fix or feature that would cause existing
functionality to not work as expected)

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

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