cubicweb #2790973 Final attribute is not correctly setted [in-progress]

The final attribute of CWAttribute is not correctly retrieve from the serialize schema during deserialization but is rather inferred from yams.BASE_TYPES, which does not allow to use used-defined types.

done in<not specified>
closed by<not specified>
patch[schema] Correctly set the final attribute of user-defined base types while deserializing the schema [folded]