Add 3-D grid analysis nudging FDDA to MPAS-A

[jherwehe]

This EPA_FDDA PR will add 3-D grid analysis nudging FDDA to MPAS-A as
an option to assist in keeping retrospective simulations dynamically
on track to improve evaluation against observations. This FDDA
development for MPAS-A (Bullock et al., 2018) nudges temperature,
humidity, and wind toward target values and is based on the comparable
FDDA feature available in WRF, including MPAS-A versions of many of the
WRF FDDA options. Enabling grid analysis nudging FDDA in MPAS-A
maintains high fidelity to the reference fields while still conserving
mass.

An extra step using init_atmosphere_model is necessary to generate the
FDDA file required for input to a subsequent MPAS-A simulation with FDDA
enabled. A script (provided to the MPAS-A maintainers) creates the FDDA
file by running init_atmosphere_model in a loop to create an initial
conditions file for each specified time (currently at 6-h intervals) of
the available reference driving data and then utilizes open source netCDF
Operator tools (NCO; https://nco.sourceforge.net/) to concatenate those
init files and add variable descriptions and mesh information.

New stream file added to streams.atmosphere under <streams>:
<immutable_stream name="fdda"
                  type="input"
                  filename_template="x4.163842.US_fdda.jul2016.nc"
                  input_interval="6:00:00"/>

New namelist.atmosphere options added under &physics:
   config_fdda_scheme = 'analysis'
   config_fdda_int = 21600.
   config_fdda_scale_min = 0.
   config_fdda_scale_max = 100000.
   config_fdda_t = true
   config_fdda_t_in_pbl = false
   config_fdda_t_min_layer = 0
   config_fdda_t_coef = 0.0003
   config_fdda_q = true
   config_fdda_q_in_pbl = false
   config_fdda_q_min_layer = 0
   config_fdda_q_coef = 0.00003
   config_fdda_uv = true
   config_fdda_uv_in_pbl = false
   config_fdda_uv_min_layer = 0
   config_fdda_uv_coef = 0.0003
(The above are example values used on the 92-km − 25-km mesh.)

New variables available for output from atmosphere_model:
   qv_fdda_new ; new water vapor mixing ratio for FDDA grid nudging (kg kg^-1)
   th_fdda_new ; new potential temperature for FDDA grid nudging (K)
   u_fdda_new ; new zonal wind component for FDDA grid nudging (m s^-1)
   v_fdda_new ; new meridional wind component for FDDA grid nudging (m s^-1)
   qv_fdda_old ; old water vapor mixing ratio for FDDA grid nudging (kg kg^-1)
   th_fdda_old ; old potential temperature for FDDA grid nudging (K)
   u_fdda_old ; old zonal wind component for FDDA grid nudging (m s^-1)
   v_fdda_old ; old meridional wind component for FDDA grid nudging (m s^-1)
   rthfddaten ; tendency of potential temperature due to FDDA (K s^-1)
   rqvfddaten ; tendency of water vapor mixing ratio due to FDDA (kg kg^-1 s^-1)
   rufddaten ; tendency of zonal wind component due to FDDA (m s^-2)
   rvfddaten ; tendency of meridional wind component due to FDDA (m s^-2)

NOTE: These EPA_FDDA code changes to MPAS-A are based on the 22 August 2022
"develop" branch of MPAS v7.3.

Reference:
Bullock Jr., O. R., H. Foroutan, R. C. Gilliam, and J. A. Herwehe, 2018:
   Adding four-dimensional data assimilation by analysis nudging to the
   Model for Prediction Across Scales – Atmosphere (version 4.0). Geosci.
   Model Dev., 11, 2897–2922. https://doi.org/10.5194/gmd-11-2897-2018

[jherwehe]

New code conflicts in src/core_atmosphere/Registry.xml were manually resolved to support this grid analysis nudging FDDA PR (#995) and have been committed (ab45f10).