Add in option to automatically select the appropriate weather model

[jacquelynsmale]

In CalcDelaysGUNW, the HyP3 entry point adds weather model data to a GUNW. As of now, there are essentially two options: "None" or "HRRR". If "HRRR" is selected and there is no weather model coverage in an area of interest, the job fails.

We could add an additional option "AUTO" for --weather-model that adds logic to add weather model data if coverage is available and, if not, does nothing and returns success.