Inconsistent data types used for axes and variables in restart files

[DusanJovic-NOAA]

The data type of axis variables in restart files is not consistent with the data type used for data variables:

$ ncdump -h control_p8_intel/RESTART/20210323.060000.fv_srf_wnd.res.tile1.nc
netcdf \20210323.060000.fv_srf_wnd.res.tile1 {
dimensions:
        xaxis_1 = 96 ;
        yaxis_1 = 96 ;
        Time = UNLIMITED ; // (1 currently)
variables:
        double xaxis_1(xaxis_1) ;
                xaxis_1:axis = "X" ;
        double yaxis_1(yaxis_1) ;
                yaxis_1:axis = "Y" ;
        double Time(Time) ;
                Time:cartesian_axis = "T" ;
                Time:units = "time level" ;
                Time:long_name = "Time" ;
        float u_srf(Time, yaxis_1, xaxis_1) ;
                u_srf:checksum = "FFFFF95324A80355" ;
        float v_srf(Time, yaxis_1, xaxis_1) ;
                v_srf:checksum = "      95502B31C2" ;

// global attributes:
                :NumFilesInSet = 1 ;
}

This happens when model is compiled using 32bit option. To make the restart files written out by the write grid component bit-identical to the restart files written out by FMS this was necessary:

https://github.com/NOAA-EMC/fv3atm/blob/develop/io/module_write_restart_netcdf.F90#L567-L573

Code that defines axis in restart files should be updated to use the same real kind for both axes and data.