Enable variable precision checkpoint-restart files (#456)

Co-authored-by: Ricky Wong <141156427+mo-rickywong@users.noreply.github.com>

Committing to main after testing

Author: iboutle

components/lfric-xios/source/lfric_xios_metafile_mod.F90

@@ -199,7 +199,11 @@ subroutine add_field(metafile, dict_field_id, mode, operation, id_as_name, legac
 
     character(20), parameter :: lfric_dict = 'lfric_dictionary'
     character(str_def) :: file_id
+#if (RDEF_PRECISION == 32)
+    integer(i_def), parameter :: dflt_prec = 4
+#else
     integer(i_def), parameter :: dflt_prec = 8
+#endif
 
     type(xios_file)    :: file
     character(str_def) :: field_id