add some tests that use g2 like the UFS_UTILS ice_blend program

[edwardhartnett]

@GeorgeGayno-NOAA says:

The ice_blend program is a small program that reads three grib2 files, does some data manipulation, and writes the result to a grib2 file. The source code is here:

[UFS_UTILS/sorc/emcsfc_ice_blend.fd at develop · ufs-community/UFS_UTILS (github.com)](https://github.com/ufs-community/UFS_UTILS/tree/develop/sorc/emcsfc_ice_blend.fd)

The consistency test is here:

[UFS_UTILS/reg_tests/ice_blend at develop · ufs-community/UFS_UTILS (github.com)](https://github.com/ufs-community/UFS_UTILS/tree/develop/reg_tests/ice_blend)