Use shr_wv_sat_qsat_liquid for qsat calculation in flux_atmOcn_diurnal_mod

The qsat calculations in flux_atmOcn_Large and flux_atmOcn_COARE_mod were recently updated to use shr_wv_sat_qsat_liquid. flux_atmOcn_diurnal_mod was *not* updated because it is not currently used in production. At some point we should probably make a similar change there.

Note that I'm about to submit a PR that introduces namelist control around this behavior for flux_atmOcn_Large and flux_atmOcn_COARE_mod. flux_atmOcn_diurnal_mod should eventually follow a similar pattern. Until then, the new config variable, aofluxes_use_shr_wv_sat, will only apply to the Large&Pond and COARE schemes.

I see that shr_wv_sat_qsat_liquid also isn't used in flux_atmocn_UA_mod, but it looks like that may be intentional because the UA formulation uses a different qsat formulation.