feat(tables): add TitleFieldsMixin

Add a table class which sets attribute `fields`
in its `Meta` class to various title fields.
For reuse in a number of entity table classes
which rely heavily on their title fields (to
reduce redundancy).

apis_ontology/tables.py

@@ -38,3 +38,8 @@ class Meta(AbstractEntityTable.Meta):
             "delete",
             "noduplicate",
         )
+
+
+class TitleFieldsMixin(tables.Table):
+    class Meta:
+        fields = ["title", "subtitle"]