Need to pass precipitation from YOG scheme to coupler

[paogorman]

Currently yog_prec is diagnosed and output but I don't think it is added to the surface water fluxes used by the coupler (e.g. would be needed by land or ocean parts of model).

CAM puts precipitation into either large-scale (precl) or convective (precc). In principle, yog could contribute to both. But for now we are considering yog to be a convection scheme, so one option would be to add yog_prec to precc in cam_diagnostics.f90 here:

https://github.com/m2lines/CAM-ML/blob/facd0cee74a7c4017501d49e9d51221fc875df8b/src/physics/cam/cam_diagnostics.F90#L1577C7-L1586C13

Then my reading of CAM is that precc gets passed to the coupler here:

CAM-ML/src/cpl/atm_import_export.F90

Line 240 in facd0ce

a2x(index_a2x_Faxa_rainc,ig) = (cam_out(c)%precc(i)-cam_out(c)%precsc(i))*1000._r8