WFS to WFS NG upgrade

Task: Removal of deprecated WFS and replace with WFS-NG

See also: http://osgeo-org.1560.x6.nabble.com/wfs-ng-vs-wfs-datastore-fight-td5261786.html and https://sourceforge.net/p/geotools/mailman/message/32457750/

Outstanding issues with WFS-NG that prevent the removal of the deprecated WFS module

• ✅ Make unit test proving backwards compatibility (feeding config file for old wfs)

• ✅ MapServer issues (GEOS-7607)

• ✅ Naming compatibility issue (GEOT-4883)

  (Andrea) "contribute a little utility wrapping store based on the GeoServer one that does the same thing as RetypingDataStore, but centralized in one place, and optional, only for those that actually need to do GML encoding. A DataUtilities.makeGmlCompatible(DataStore) -> DataStore of sorts." (Mark Prins) adding a hint or connection param "use_wfs_legacy_naming" making WFSDataStore#createTypeNames() work with the hint while cooking up the names

  Default behaviour should be wfs legacy naming.

• ✅ count() not using resultType=hits (GEOT-5222) (old WFS did)

• ✅ proper exception reporting (GEOT-5134)

Other (non-blocking issues) WFS-NG

• ✅ GEOT-5132 - encoding spatial filters (WFS 2.0- unsupported by old WFS module anyway)
• GEOT-5246 (Complex Features - unsupported by old WFS module anyway)