Allow FVCOM to be used in Warm and Cold Starts

[dmwright526]

DESCRIPTION OF CHANGES:

Updates to the fvcom tools now require the use of two additional input variables:

1. A flag for "warm" or "cold" start. The "warm" flag now allows for the use of sfc_data.nc files generated from a restart of UFS-SRW. The "cold" flag will read in sfc_data.nc files generated directly from chgres_cube.
2. A string of the desired time slice in the fvcom data file.

One additional variable has been created for the config file (fvcom_wcstart) to define if the run will be a "warm" start or "cold" start. The creation of the time string is done in the exregional_make_ics.sh script and uses existing user defined variables (DATE_FIRST_CYCL, CYCL_HRS) to complete the task.

This will solve issue: https://github.com/NOAA-EMC/regional_workflow/issues/619

TESTS CONDUCTED:

Tests were performed on Hera and Jet for the RRFS NA grid and a custom grid over the Great Lakes.

DEPENDENCIES:

These changes are dependent upon ufs-community/UFS_UTILS#595.

DOCUMENTATION:

[JeffBeck-NOAA]

@dmwright526, I tested this PR with a cold start case using an FVCOM data set, and ran a second test with FVCOM="False". Results are as expected for each. Will merge now.