[Buildbot][NVHPC] Add LLDB support (#903)

RFC: https://discourse.llvm.org/t/rfc-add-native-support-for-fortran-in-lldb/91034

## Summary

- enable LLDB in the NVHPC x86_64 Linux builder
- add the LLDB builder tag so the builder is discoverable under LLDB
- run `check-lldb` alongside the existing LLVM, MLIR, and Flang checks

## Testing

- `python3 -m py_compile buildbot/osuosl/master/config/builders.py
buildbot/osuosl/master/config/workers.py`
- targeted static validation of the NVHPC builder, project/check lists,
and worker references
- `git diff --check`