Closes #6414: Enable assigning prefixes to various object types (#17692)

* Replace site FK on Prefix with scope GFK

* Add denormalized relations

* Update prefix filters

* Add generic relations for Prefix

* Update GraphQL type for Prefix model

* Fix tests; misc cleanup

* Remove prefix_count from SiteSerializer

* Remove site field from PrefixBulkEditForm

* Restore scope filters for prefixes

* Fix scope population on PrefixForm init

* Show scope type

* Assign scope during bulk import of prefixes

* Correct handling of GenericForeignKey in PrefixForm

* Add prefix counts to all scoped objects

* Fix migration; linter fix

* Add limit_choices_to on scope_type

* Clean up cache_related_objects()

* Enable bulk editing prefix scope

netbox/utilities/testing/base.py

@@ -1,5 +1,6 @@
 import json
 
+from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.postgres.fields import ArrayField, RangeField
 from django.core.exceptions import FieldDoesNotExist
@@ -120,6 +121,10 @@ class ModelTestCase(TestCase):
                 else:
                     model_dict[key] = sorted([obj.pk for obj in value])
 
+            # Handle GenericForeignKeys
+            elif value and type(field) is GenericForeignKey:
+                model_dict[key] = value.pk
+
             elif api:
 
                 # Replace ContentType numeric IDs with <app_label>.<model>