add text orientation property to transcriptions (editable in admin)

arkindex/documents/admin.py

arkindex/documents/indexer.py

...ex/documents/migrations/0044_transcription_orientation.py

arkindex/documents/models.py

arkindex/documents/serializers/ml.py

arkindex/documents/serializers/search.py

arkindex/documents/tests/commands/test_reindex.py

arkindex/documents/tests/test_create_transcriptions.py

arkindex/documents/tests/test_edit_transcriptions.py

arkindex/documents/tests/test_indexer.py

arkindex/documents/tests/test_search_api.py

arkindex/documents/tests/test_transcriptions.py

arkindex/sql_validation/indexer_prefetch.sql