restore to match published version of v4.3

[jclerman]

Summary

Before this PR, the version of the ontology in main branch differed from what we published (as RadLex v4.3) in late 2025 in several respects. This PR brings main into agreement with that "true" v4.3. Specifically:

• switch values from http://www.radlex.org/RID/Preferred_name to http://www.w3.org/2000/01/rdf-schema#label (all such values have language-tag en)
• switch values from http://www.radlex.org/RID/Preferred_name_German to http://www.w3.org/2000/01/rdf-schema#label (all such values have lang-tag de)
• move the RadLex IDs from http://www.w3.org/2000/01/rdf-schema#label to a dedicated annotation-property http://www.radlex.org/RID/RadLexID
• consolidate cross-references to other terminologies/ontologies: In general, take the values that were on dedicated annotation properties (e.g. http://www.radlex.org/RID/UMLS_ID) and move them to http://www.radlex.org/RID/ExternalRefID, with a prefix indicating the terminology - e.g., assert UMLS:C001234 on ExternalRefID.

Finally, retain annotations asserted on annotations (via the OWL "reified" annotation convention), for two OWL annotation properties:

• http://www.radlex.org/RID/UMLS_Term - 1323 assertions
• http://www.radlex.org/RID/name - 1601 assertions