Need to add area correction factors for fluxes in the nuopc cap

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(For some background, see ESCOMP/CMEPS#84).

For fluxes, we generally need a correction factor between the model's internal areas and the grid cell areas on the mesh file that is used to create the mappings between components. For glc, it's tricky to figure out which fields need these area corrections and which ones don't because of the non-standard way in which some fields are mapped. I think (but am not 100% sure) that we should be doing area corrections for the fluxes sent from glc to other components: the heat flux sent to land, and the runoff fluxes sent to the ocean (or theoretically to the ice model).

I'm pretty sure we do not want to do these area corrections for the other glc -> lnd fields. (In section 3.4 of https://docs.google.com/document/d/144PZ63gwpz875U4EYEI7NuxnF__V955QJOxV9LcEAL0/edit# , I showed why we do not want to do area correction for these (or at least why we don't need to do area correction... I'm not 100% sure that it is a problem to do area correction, but I think it would be).

For lnd -> glc fluxes (currently just smb/qice), with the way we are doing the smb renormalization, I'm pretty sure we do not want to do these area corrections: see this comment:

https://github.com/ESCOMP/CMEPS/blob/5dc55a8913c1687bef673d508d87c300a46c2754/mediator/med_phases_prep_glc_mod.F90#L1011-L1025

@mvertens @whlipscomb @Katetc

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@mvertens @whlipscomb @KateC in reviewing some open issues, this one came to my attention as something needed for CESM3.

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Sorry, meant to tag @Katetc there.