WMO GRIB2 CodeFlag and Template definitions

[lesserwhirls]

Once wmo-im/GRIB2#77 (comment) is solved, we can update the WMO CodeFlag and Template xml files to the latest version. Using the latest versions, there is no way to link a CodeFlag with a discipline using the XML files provided by the WMO.

[lesserwhirls]

Opened a new issue on the wmo-im/GRIB2 repo to improve visibility.