Align SM query result set with REST variant

The UML for RESULT_SET & co should be aligned with the way it appears in the REST, as that is the one agreed by majority.

• some attribute names needs to be changed or needs to me made optional:
  query_name => name
  source_aql_ptext => q
  etc.

• add 'meta'

• change 'rows' to be Any[]

for row_column, aql_path should become path and be optional