Add firewx_gridspecs source code to rrfs_utl

[BenjaminBlake-NOAA]

DESCRIPTION OF CHANGES:

The RRFS fire weather nest will be implemented with RRFS version 1, and it is designed to replicate the current capability of the operational NAM fire weather nest. A source code called firewx_gridspecs is needed in order to read in a latlons_corners text file (produced by the UPP), and it creates the WGRIB2 grid specs for the fire weather output grid.

TESTS CONDUCTED:

Successfully built the firewx_gridspecs source code on Hera and WCOSS2.

DEPENDENCIES:

This code is needed for a future PR to rrfs-workflow for adding the RRFS fire weather nest post-processing capability.

DOCUMENTATION:

Let me know if I need to add any documentation with this PR.

ISSUE (optional):

Related to issue 15 in the rrfs-workflow repository:
NOAA-EMC/rrfs-workflow#15

CONTRIBUTORS (optional):

I am not too familiar with using cmake, so I followed what @MatthewPyle-NOAA did for the RRFS bufr codes in the bufrsnd directory.

[christopherwharrop-noaa]

Can you please remove the makefile? This repository uses a CMake build system.

[BenjaminBlake-NOAA]

Sure no problem, I just removed the makefile. A few other directories here contain makefiles, specifically bufrsnd.fd/rrfs_bufr.fd, bufrsnd.fd/rrfs_sndp.fd, bufrsnd.fd/rrfs_stnmlist.fd, and lightning.fd, so I wonder if those are also not needed and could be removed.

[christopherwharrop-noaa]

Thank you @BenjaminBlake-NOAA . Thank you for pointing those other makefiles out. They should also be removed, but aren't really in the scope of this PR.

[christopherwharrop-noaa]

Thank you for addressing my concern.

[BenjaminBlake-NOAA]

@christopherwharrop-noaa No problem, thanks for taking the time to review.