Change GRIB2 parameter names and vertical levels for nc2grb

[GwenChen-NOAA]

Description

Based on users' feedback, this PR do the following:

1. Change GRIB2 parameter names DLWRF -> NLWRF and DSWRF -> NSWRF
2. Change the vertical level of ocean 3D variables (WTMP, SALIN, UOGRD, and VOGRD) from "%g m below water surface" to "%g m below sea level"
3. Round up depth numbers to integer (e.g. 4481.0625 -> 4481 m)

Type of change

• Update

Change characteristics

• Is this a breaking change (a change in existing functionality)? NO
• Does this change require a documentation update? NO

How has this been tested?

Tested on WCOSS2 using sample netcdf files and successfully generated grib2 files.

Checklist

• Any dependent changes have been merged and published
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• New and existing tests pass with my changes
• I have made corresponding changes to the documentation if necessary

[aerorahul]

@GwenChen-NOAA
These scripts (in gfs-utils) are no longer used in the GFS/GEFS. They will be removed in the future to eliminate this duplication.
The scripts are in the global-workflow and you have updated them in NOAA-EMC/global-workflow#2611.

[aerorahul]

looks good.
thanks!