GEOSgcm v12: Updates needed for instance files and RRTMGP

[mathomp4]

Recently GEOSgcm v12 moved to RRTMGP, and for that we added code in gcm_run.j et al to transform files here in GOCART at run time.

For example, in dust we have:

aerosol_radBands_optics_file:      ExtData/chemistry/AerosolOptics/v0.0.0/x/opticsBands_DU.v15_3.RRTMG.nc 

which tells the model to use files developed for RRTMG. But now with RRTMGP, we need that line to be:

aerosol_radBands_optics_file:      ExtData/chemistry/AerosolOptics/v0.0.0/x/opticsBands_DU.v15_3.RRTMGP.nc 

So in gcm_run.j et al, we do:

set instance_files = `/bin/ls -1 *_instance*.rc`
foreach instance ($instance_files)
   /bin/mv $instance $instance.tmp
   cat $instance.tmp | sed -e '/RRTMG/ s#RRTMG#RRTMGP#' > $instance
   /bin/rm $instance.tmp
end

where we in place change the RRTMG to RRTMGP. And, recently, a bug was found in that code (see GEOS-ESM/GEOSgcm_App#696) and a fix proposed.

The "right" way to do this, though, is edit the instance files, change RRTMG to RRTMGP, tag, update GEOSgcm v12, and there you go.

That said, if we want to support RRTMG and RRTMGP at the same time, perhaps we need to have two copies of the instance files? Or perhaps they should be "templates" and detemplated by gcm_setup? I'm not sure.

cc: @sdrabenh @amdasilva @wmputman