WL#11087: Ellipsoidal ST_Validate

ST_Validate currently only supports computations in Cartesian spatial reference
systems (SRSs). This WL extends ST_Validate to detect that its parameter is in a
geographic (ellipsoidal) SRS and to compute on the ellipsoid.

Projected SRSs and SRID 0 will still return the same result as before. If the
SRID refers to a geographic SRS, the result will be different.

This WL should remove function check_geometry_valid() and class
Geomcoll_validity_checker.