fcl-db: sqlDB: add more informations to schema query for table columns (SchemaType=stColumns)
(Values for COLUMN_DATATYPE are not compatible across TSQLConnections, but are proprietary)

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@25721 3ad0048d-3df7-0310-abae-a5850022a9f2