clean up unused fields

We should clean up fields that are no longer used. Check with https://gitlab.gwdg.de/MPIWG/Department-II/ismi-cidoc-model/-/wikis/cleaned-openmind-data-model

• codex_indexmeta_folder
• codex_is_alias
• codex_distinguishing_features
• codex_notes_on_ownership
• codex_url_digitized_codex
• COPY_EVENT
• person_is_prime_alias_name_of
• person_arabic_notes
• text_notes_arabic
• text_text_arrangement
• witness_diagrams_and_illustratio
• witness_notes_arabic
• witness_other_features
• witness_page_layout
• witness_scans
• witness_notes_on_collation_and_c
• witness_notes_on_ownership
• witness_notes_on_title_author
• witness_was_studied_by
• witness_was_copied_in_as