Update retrospective url generaton function to include zarr s3

[sepehrkrz]

Current base url list for retrospective files does not include the CIROH-developed zarr archive for NWM 2.1 retrospective output. Those files are here:
https://ciroh-nwm-zarr-retrospective-data-copy.s3.amazonaws.com/index.html#noaa-nwm-retrospective-2-1-zarr-pds/

See here:

nwmurl/nwmurl/urlgennwm.py

Lines 164 to 169 in d2b9676

	urlbasedict_retro = {
	1: "https://noaa-nwm-retrospective-2-1-pds.s3.amazonaws.com/",
	2: "s3://noaa-nwm-retrospective-2-1-pds/",
	3: "https://ciroh-nwm-zarr-retrospective-data-copy.s3.amazonaws.com/noaa-nwm-retrospective-2-1-zarr-pds/",
	4: "https://noaa-nwm-retrospective-3-0-pds.s3.amazonaws.com/CONUS/netcdf/",
	}

[jameshalgren]

@sepehrkrz Is this already complete? Is the only task here to insert a demonstrative test case?

[jameshalgren]

@sepehrkrz Is this already complete? Is the only task here to insert a demonstrative test case?

Answering my own question: No.

The need here is for s3://... and the only protocol for this endpoint we have set up is https://...

[jameshalgren]

@karnesh
Do we need both s3 and https entries in the list?