feat(relations): allow more generic relation tables

This extends the list of possible relation table classes by also looking
at the MRO of the target of the relation. This way it possible to make
one table for a relation between two parent classes that is used for
displaying relations between two child classes of those parent classes.

apis_core/relations/templatetags/relations.py

@@ -2,7 +2,7 @@
 from django.contrib.contenttypes.models import ContentType
 from django.db.models import Case, Q, Value, When
 
-from apis_core.generic.helpers import first_member_match, module_paths
+from apis_core.generic.helpers import first_member_match, module_paths, mro_paths
 from apis_core.relations.models import Relation
 from apis_core.relations.tables import RelationsListTable
 from apis_core.relations.utils import relation_content_types, relation_match_target
@@ -58,11 +58,16 @@ def relations_from(from_obj, relation_type: ContentType = None):
 
 @register.simple_tag(takes_context=True)
 def relations_list_table(context, relations, target=None):
-    table_modules = module_paths(
-        type(context["object"]),
-        path="tables",
-        suffix=f"{target.name.capitalize()}RelationsTable",
-    )
+    suffixes = ["RelationsTable"]
+    if target:
+        suffixes.extend(
+            f"{module[-1]}RelationsTable" for module in mro_paths(target.model_class())
+        )
+    table_modules = ()
+    for suffix in suffixes:
+        table_modules += module_paths(
+            type(context["object"]), path="tables", suffix=suffix
+        )
     table_class = first_member_match(table_modules, RelationsListTable)
     if target:
         relations = [