Add support for Z/M geometries in WFS Client

[FroehDo]

Feature description

In QGIS (tested up to 3:34) a WFS-T service can only be modified if it contains X/Y Features only. Modifiactions to a WFS-T with XYZ or M geometries (e.g. provided by TinyOWS or geoserver) will fail. The service will also only be e.g. "Polygon" in the Properties even if the Service is PolygonZ. A Service with Z / M Coordinates could be provided with either untouched values for Z / M (in modification) or with dummy 0 values on adding new features / vertices.

Additional context

No response

[elpaso]

M is probably not doable because the lack of support by GML.

Z can be implemented by either explicit user setting or by examining a NOT NULL feature, the latter won't work if the layer is empty.

[FroehDo]

Loading the WFS with PolygonZ geoms in the first place is a way better approach, true. For your proposed solution I'd implement both: Why not try to make a guess based on the first non-null feature and use that to pre-set some checkbox? This allows the user to override the initial guess in cases it was wrong or XY geoms are desired for some reason.