Update orography code for low-res grids

[GeorgeGayno-NOAA]

DESCRIPTION OF CHANGES:

Low-resolution grids are defined as C24/C18/C12.

1 - Updates to the orography code:

• read_global_orog and read_global_mask - A check was added to ensure the i/j-dimensions of the global data match the dimensions passed in as arguments.
• qc_orog_by_ramp was updated to read the j-dimension of the RAMP data from the file itself, instead of being declared in the routine. This made writing a unit test easier.
• makemt2 - variable "maxsum" is now calculated dynamically instead of being hardwired. The hardwired value was not large enough for grids coarser than C48.
• make_mask - variable "maxsum" is not used and was removed.
• remove_isolated_pts - This routine was originally written for the global gaussian grid. Some of the logic did not work for FV3 tiles. To fix, the check along the "east/west" tile edges was removed. Also removed was logic that was (I believe) used for reduced gaussian grids (where the number of 'i' points decreased toward the poles).
• All I/O routines were updated to use the F90 NetCDF routines.
• Minor corrections to the Doxygen for a few routines.

2 - New unit tests for the following routines/functions:

• find_nearest_pole_points
• find_poles
• get_index
• get_lat_angle
• get_lon_angle
• get_xnsum
• get_xnsum2
• get_xnsum3
• inside_a_polygon
• latlon2xyz
• minmax
• qc_orog_by_ramp
• read_global_mask
• read_global_orog
• read_mask
• read_mdl_dims
• read_mdl_grid_file
• remove_isolated_pts
• transpose_mask
• transpose_orog

TESTS CONDUCTED:

• Compile branch on all Tier 1 machines using Intel (Orion, Jet, Hera, Hercules and WCOSS2).
• Compile branch on Hera using GNU.
• Compile branch in 'Debug' mode on WCOSS2. Done on Cactus using 64d26a4. There were no warnings.
• Run unit tests locally on any Tier 1 machine using both Intel and GNU. Done on Cactus (Intel) using 64d26a4. All tests passed.
• Run grid_gen consistency tests locally on all Tier 1 machines. Done on Hercules, Jet, Cactus and Orion using 64d26a4. All tests passed as expected.
• Compile with Doxygen. Done on Cactus using 64d26a4. The orog.fd code had no warnings.

Describe any additional tests performed.

• Using 64d26a4, a C12 global uniform test was created on Hercules using ./driver_scripts/driver.hercules.sh

DEPENDENCIES:

None.

DOCUMENTATION:

Doxygen successfully created. See above.

ISSUE

Fixes #1000.

RELATED ISSUES

ufs-community/ufs-weather-model#2508