Mark API-breaking changes of T16765 as deprecated:
- Removal of mitk::PlaneGeometryDataMapper2D::SetDatastorageAndGeometryBaseNode()
- Removal of QmlMitkRenderWindowItem::SetPlaneNodeParent()
We need to mark these changes as deprecated in order to merge T16765 after the current release. SetPlaneNodeParent() is in an experimental module. We might only mark the first removal as deprecated.