feat(generic): add a repr dunder method to the GenericModel

This method lets us print more meaningful debug messages without having
to add the ID to the str dunder method.

apis_core/generic/abc.py

@@ -6,6 +6,9 @@
 
 
 class GenericModel:
+    def __repr__(self):
+        return super().__repr__() + f" (ID: {self.id})"
+
     @classmethod
     def get_listview_url(cls):
         ct = ContentType.objects.get_for_model(cls)