Clone methods correctly implemented for bidirectional relationships
Many clone methods do not take into account that links to single objects or collection items require handling of bidirectionality during cloning, otherwise the other object does not know about the new clone, but should (in many cases).
See Revision d014205f as an example.
#7357 fix failing converter test in service layer after fixing typeDesignation.clone
ref #7357 removing workaround for incomplete DerivedUnit.cone() in DerivedUnitConverter
ref #7357 fix test for CategorialData.clone and move it from DescriptionElementTest to CategoricalDataTest