Modify NUOPC cap to accept separate runoff fluxes from the GLC component

[billsacks]

@mvertens is making changes in CESM so that solid & liquid runoff fluxes from CISM are routed to the runoff model rather than directly to the ocean. Currently, for backwards compatibility, she is making the default behavior be that these runoff fluxes from GLC get combined with the other runoff terms in MOSART so that the ocean gets the combined fluxes that it already imports in its cap. However, at the request of @gustavo-marques, the long-term behavior will be for the GLC-derived runoff fluxes to be routed separately through MOSART and then kept separate in the mediator, so that MOM can distinguish between GLC-derived runoff and LND-derived runoff for the sake of enthalpy calculations and diagnostics.

So MOM's NUOPC cap should be updated to import the new solid and liquid runoff fluxes from GLC through MOSART that @mvertens is adding to CMEPS, and then these fluxes should be handled in the appropriate way in MOM. Once this is done, we can change the MOSART behavior so that we use these new fluxes instead of adding the GLC terms to the existing runoff fluxes.

[billsacks]

@alperaltuntas - @gustavo-marques thought you'd be the best one to handle this. I'm happy to talk more with you if you'd like. This should be in place before the July 31 science functionality freeze if we're going to have an active (evolving) ice sheet in the CESM3 science simulations, which is currently the tentative plan.

[gustavo-marques]

@billsacks, thanks for coordinating this!

[alperaltuntas]

@billsacks, I've just started looking into this. Seems like ESCOMP/MOSART#94 implemented this feature in MOSART. Do we have a branch or PR ready for CMEPS as well. And, any tips (.e.g xml or namelist changes) on how I should test my upcoming MOM6 changes?

[mvertens]

@alperaltuntas - see ESCOMP/CMEPS#463. This has already been merged. And CISM has been modified to send fields with new names - ESCOMP/CISM-wrapper#100
Also see https://github.com/ESCOMP/CDEPS and ESMCI/ccs_config_cesm#174.
This implementation required changes to multiple repositories - but they are all merged at this point.