general machanism for getting spatial_id_name from netcdf file

this is too hard-coded

https://github.com/EC-USGS/pynhm/blob/ef9e439a515c2adc4620b1e686985c6a56757597/pynhm/utils/netcdf_utils.py#L141

require global metadata in the file saying "generic=specific"?
in absence of global metadata, have a default to the non-time dimension?
is there another way in parameters or control?

Start by reading the referenced pynhm/utils/netcdf_utils.py around line 141 and compare it with the corresponding pywatershed code. Determine how spatial_id_name is currently obtained, then clarify the intended precedence between global metadata, the non-time dimension fallback, and parameters or control before defining completion criteria.

Written by the indexing model from the issue text.