Add/review crs for flet data

Add (or review for accuracy if it already exists) crs information to flet datasets, which likely have the same crs (but please check this):

• s3://mdmf/gdp/flet_narr.zarr
• s3://mdmf/gdp/flet_stns.zarr

They have the following THREDDS catalog entries, if that is helpful to have:

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