Remove need for Spatial Dialects

[maesenka]

The biggest problem with the current Hibernate Spatial design is the need for SpatialDialects. In Hibernate 6 we should no longer need them.

Currently SpatialDialects exist mainly to:

1. create and register the spatial Hibernate Types: GeolatteGeometryType and JTSGeometryType;
2. registering the spatial functions implemented for the database.
3. register the column type name for DDL operations (via the registerColumnType() method)

For 1), we can move the type contributions out of the SpatialDialect and in a separate TypeContributor implementation that is provided by the Spatial module.

For 2) we can add a FunctionContributor contract (see proposa #4108) and use that to register the spatial functions into the QueryEngine's function registry.

For 3), we can move the column type registration to the (parent) Dialect since it introduces no dependencies. This depends on proposal #4088 (Introduce notion of SQL type code).

[maesenka]

Work has been started on this. PR will follow soon so Hibernate-spatial can be re-enabled from that point on.