Add new submodule for an alternate ROF model WRF-Hydro

There is a team working on coupling WRF-Hydro into CTSM, CAM, and CESM. @rcabell @scrasmussen @felfelan among others.

The repository is here:

https://github.com/NCAR/wrf_hydro_nwm_public

In the shorter term we will bring this into CTSM as a new submodule. Longer term we may have it as a package that's built with mizuRoute. But, we'll have to see how that works.

NOTE: WE WILL NOT INCLUDE THIS IN THE RELEASE BRANCH for cesm3_0. So we will need to either have a branch for this or remove it on the release branch. I suggest the latter since it's lower overhead. We just need to remember to do it.

Definition of Done:
- [ ] Figure out how the WRF-Hydro NUOPC cap will work in coupling into CESM
- [ ] Figure out what tests we will want to have for it
- [ ] Figure out how to get it to build in the CESM system
- [ ] Add it to the submodules in .gitmodules in a PR to bring into master
- [ ] Add some tests for it in the initial PR
- [ ] Add a PR into CMEPS to pass the additional fields needed
- [ ] PR to bring in new CMEPS and new tests that extend the functionality