Update MSIS used for WACCM upper boundary to NRLMSIS 2.1

### What is the feature/what would you like to discuss?

The proposal here is to update the MSIS empirical model used for WACCM upper boundary conditions with NRLMSIS 2.1. This has a Fortran90 interface which is more supported in CESM/CAM than the Fortran77 interface in `msise00.F90`, in addition to scientific updates.

See:
https://doi.org/10.1029/2020EA001321
https://doi.org/10.1029/2022JA030896

### Is there anyone in particular you want to be part of this conversation?

@dan800 et al.

### Will this change (regression test) answers?

Yes

### Will you be implementing this enhancement yourself?

Yes