Refactor `gpf_wfs_get_features`

[esgn]

This is the most complex tool and is currently hard to use by a model.

• introduce geometry references instead of geometric objects => done in Redesign WFS querying with structured filters and reusable feature refs #38
• extract a get_feature_by_id tool => done in gpf_wfs_get_feature_by_id #52
• Split gpf_wfs_get_features tool in multiple specific tools with their own outputschema and test. gpf_wfs_get_features is polymorph in terms of response for new
• Rethink the fact of never returning any geometry. Maybe a filter for centroid, bbox, simplified geometry should be implemented