Add "easy" GEOS-IT restart remapping

[mathomp4]

@wmputman has said easy remapping from GEOS-IT (like we have from MERRA2) would be useful to have in remap_restarts.py.

Once @wmputman can point us to where the GEOS-IT restarts are, we could then add an option to make it so.

Note: We'd of course need to know what the horz and vert resolutions are, what the ocean used is, and what the land bcs used is. But once we know that, I believe @weiyuan-jiang could quickly incorporate it.

[biljanaorescanin]

I was using for GEOS-IT this path for Bill, are you thinking about those or something else?
/discover/nobackup/projects/gmao/geos-it/dao_ops/archive/d5294_geosit_jan18/rs/
it is CS ocean and NL3 land. Everything else remap restarts automatically picks up already. I think its is 72 lev and C180 res.
That dir only has tar files for two days 14th and 28th.

[mathomp4]

@biljanaorescanin Hmm. When I look in there, I see restarts for every day at 3, 9, 15 and 21z.
What year/month do you only see a set of two days?

[mathomp4]

@biljanaorescanin is correct. The only guaranteed restarts are the 14th and 28th. 2024 seems to have every day, but not in the past...