Add option to read ocean _data_ using ExtData

[sanAkel]

This PR adds an optional capability to read in ocean boundary conditions:

• From netcdf formatted files, currently only binary formatted files are supported. The netcdf files are read via ExtData.
• This PR retains the current binary inputs as default, whereas the netcdf inputs are optional, turned ON by setting: OCEAN_EXT_DATA:.TRUE in AGCM.rc, in which case the user is expected to provide an .rc file with the correct format (see below for an example).

Reg. input netcdf files:

• In coupled configuration one needs to provide ocean color (KPAR) only (without using OBIO, with DO_OBIO=0).
• In uncoupled configuration we need KPAR, SST and sea ice concentration.
• Support for ⬆️ is provided via Support for ocean datasets using ExtData GMAO_Shared#245

The changes in this PR are zero-diff in default mode (binary inputs), and for the netcdf inputs, the differences are within the expected range (accounting for differences in ExtData and MAP_ReadForcing, as per @bena-nasa). This was checked in:

• uncoupled mode.
• coupled mode.

Example .rc file:

PrimaryExports%%
# -------------|-------|-------|--------|----------------------|--------|--------|-------------|----------|
#  Import      |       |       | Regrid |        Refresh       | OffSet | Scale  | Variable On |   File   |
#  Name        | Units | Clim  | Method |     Time Template    | Factor | Factor |     File    | Template |
# -------------|-------|-------|--------|----------------------|--------|--------|-------------|----------|

DATA_ICE         '1'    N         N               0               none   none FRSEAICE /discover/nobackup/sakella/extData_uncoupled/scratch_orig/extData_uncoupled.geosgcm_surf.%y4%m2%d2_%h230z.nc4
DATA_SST         'K'    N         N               0               none   none TS       /discover/nobackup/sakella/extData_uncoupled/scratch_orig/extData_uncoupled.geosgcm_surf.%y4%m2%d2_%h230z.nc4
DATA_KPAR        'm-1'  Y         N               0               none   none KPAR     /discover/nobackup/sakella/BCs/test_ocean_ext/prepare_ocnExtData/clim_kpar_GMAO2022.nc4
%%

[sanAkel]

@sdrabenh please consider merging this PR BEFORE #551
🙇‍♂️

[sdrabenh]

@mathomp4 it looks like gfortran is complaining about a type cast. @sanAkel would you mind fixing so both compilers are happy? Thanks

[mathomp4]

@mathomp4 it looks like gfortran is complaining about a type cast. @sanAkel would you mind fixing so both compilers are happy? Thanks

I can fix it. it's something I recognize.

[sanAkel]

@mathomp4 🙏 for the quick fix

[sdrabenh]

@mathomp4 thanks! I don't know how you spot these things so easily

[sanAkel]

@mathomp4 thanks! I don't know how you spot these things so easily

yeah! Especially those spaces: " " 😮