[ENHANCEMENT] Use Herbie for all weather model data retrieval?

[nate-kean]

Herbie is a package for downloading weather model data: https://herbie.readthedocs.io/en/stable/. Right now, we use it for HRRR, but it actually supports all of the weather models that RAiDER supports. Potentially, we could use Herbie for all of RAiDER's weather model data retrieval, which could serve to vastly simplify and consolidate our weather model classes.

[nate-kean]

It turns out that GMAO and MERRA2, where a lot of our recent churn has been, are not supported in Herbie after all. If we move forward with this, we may still stand to benefit from making the fetch routines for the rest of the support models more consistent, but we will still have to support GMAO and MERRA2 with something else.