Add landuse pft data tools as an optional submodule in CTSM

The landuse pft data tools are now in github in ESCOMP, and they should be included as an optional checkout in CTSM. The repository to add is:

https://github.com/ESCOMP/CTSM-LUH-LandUseDataPrepTools

Definition of Done:
- [ ] Check in the latest changes that created the newest datasets, as is
- [ ] Create a tag for the tools
- [ ] Add the tag used to create datasets to the CMIP repository: https://github.com/NCAR/CMIP7_inputdata_processing
- [ ] Add LandUseDataPrep under the tools subdirectory in .gitmodules
- [ ] Add testing for Derecho to verify it works