reordered phenomenon dictionaries

non-functional change

re-ordered um_cf_map.py and grib_cf_map.py to simplify future reviews.

The dictionaries are now in 
 * import
  * dict_name
 * export
  * dict_name
order.

This will allow iris-code-generators processes to recreate these dictionaries in the same order as they currently exist.  Once these processes are in place, the code reviews will be simpler, providing content change but not reordering.