[OAPIF provider] Add support for filtering based on OGC API Features …

…Part 3

This requires server /conformance to declare at least:
- http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/filter
- http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/features-filter
- http://www.opengis.net/spec/cql2/1.0/conf/cql2-text
- http://www.opengis.net/spec/cql2/1.0/conf/basic-cql2

The /collections/{collid}/queryables endpoint is requested to get the
queryable properties.

And it can use the following extra conformance classes:
- http://www.opengis.net/spec/cql2/1.0/conf/advanced-comparison-operators:
  for IN, BETWEEN, LIKE
- http://www.opengis.net/spec/cql2/1.0/conf/case-insensitive-comparison:
  for ILIKE
- http://www.opengis.net/spec/cql2/1.0/conf/basic-spatial-operators:
  for intersects(geomcolumn, geomFromWkt('POINT(x y)')) and
  bbox_intersects(geomcolumn, geomFromWkt('WKT LITERAL'))

src/providers/wfs/CMakeLists.txt

@@ -28,12 +28,14 @@ set(WFS_SRCS
   oapif/qgsoapifcollection.cpp
   oapif/qgsoapifconformancerequest.cpp
   oapif/qgsoapifcreatefeaturerequest.cpp
+  oapif/qgsoapifcql2textexpressioncompiler.cpp
   oapif/qgsoapifdeletefeaturerequest.cpp
   oapif/qgsoapifpatchfeaturerequest.cpp
   oapif/qgsoapifputfeaturerequest.cpp
   oapif/qgsoapifitemsrequest.cpp
   oapif/qgsoapifoptionsrequest.cpp
   oapif/qgsoapifprovider.cpp
+  oapif/qgsoapifqueryablesrequest.cpp
   oapif/qgsoapifutils.cpp
 )