Add convective gustiness to (ocean) surface flux calculation

[megandevlan]

We're working on a way to modify the calculation of surface fluxes (over ocean first) to include the impacts of convective gustiness. A few years ago, @swrneale implemented the modifications needed to do this in a branch of CAM, which mostly involved modifications to a few cime scripts (shr_flux_mod.F90 and seq_flux_mct.F90) to add a gustiness term to the calculation of the surface wind magnitude vmag based on an input convective precipitation estimate from CAM.

In the new CMEPS architecture, it seems this will involve modifying vmag in cmeps/cesm/flux_atmocn/shr_flux_mod.F90 in the case where ocn_surface_flux_scheme=0. I suspect the (nearest?) equivalent to seq_flux_mct.F90 is cmeps/mediator/med_phases_aofluxes_mod.F90, though I imagine a few other modifications might be necessary in esmFldsExchange_cesm_mod.F90, fd_cesm.yaml to pass the convective precipitation to the coupler.