(dev/emc) Regional IC/LBC routines allows only gfs nemsio string as global attribute source (reopened)

[chan-hoo]

• This is the same as Regional IC/LBC routines allow only 'nemsio' as global attribute 'source' #95, which was closed without merged.
• The regional IC/LBC routines allows only one source string "FV3GFS GAUSSIAN NEMSIO FILE" as the global attribute source of the input data even though other input types such as "FV3GFS GAUSSIAN NETCDF FILE" and "FV3GFS GRIB2 FILE" are available in chgres_cube.
• This restriction makes the LAM/LAM-DA experiments using netcdf and grib2 files for IC fail during initialization.
• Since the 'nemsio' format is not provided in the real-time data directory any more and it is replaced by 'netcdf', this part of the source string should be modified.