Add/review crs for stageiv_combined data

Add (or review for accuracy if it already exists) crs information to stageiv_combined dataset:

• s3://mdmf/gdp/stageiv_combined.zarr

It has the following THREDDS catalog entry, if that is helpful to have:

• https://cida.usgs.gov/thredds/catalog.html?dataset=cida.usgs.gov/thredds/stageiv_combined/