Closes #19924: Record model features on ObjectType (#19939)

* Convert ObjectType to a concrete child model of ContentType

* Add public flag to ObjectType

* Catch post_migrate signal to update ObjectTypes

* Reference ObjectType records instead of registry for feature support

* Automatically create ObjectTypes

* Introduce has_feature() utility function

* ObjectTypeManager should not inherit from ContentTypeManager

* Misc cleanup

* Don't populate ObjectTypes during migration

* Don't automatically create ObjectTypes when a ContentType is created

* Fix test

* Extend has_feature() to accept a model or OT/CT

* Misc cleanup

* Deprecate get_for_id() on ObjectTypeManager

* Rename contenttypes.py to object_types.py

* Add index to features ArrayField

* Keep FK & M2M fields pointing to ContentType

* Add get_for_models() to ObjectTypeManager

* Add tests for manager methods & utility functions

* Fix migrations for M2M relations to ObjectType

* model_is_public() should return False for non-core & non-plugin models

* Order ObjectType by app_label & model name

* Resolve migrations conflict

netbox/ipam/models/ip.py

@@ -1,5 +1,6 @@
 import netaddr
 from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.db.models import F
@@ -7,7 +8,6 @@ from django.db.models.functions import Cast
 from django.utils.functional import cached_property
 from django.utils.translation import gettext_lazy as _
 
-from core.models import ObjectType
 from dcim.models.mixins import CachedScopeMixin
 from ipam.choices import *
 from ipam.constants import *
@@ -917,7 +917,7 @@ class IPAddress(ContactsMixin, PrimaryModel):
 
         if self._original_assigned_object_id and self._original_assigned_object_type_id:
             parent = getattr(self.assigned_object, 'parent_object', None)
-            ct = ObjectType.objects.get_for_id(self._original_assigned_object_type_id)
+            ct = ContentType.objects.get_for_id(self._original_assigned_object_type_id)
             original_assigned_object = ct.get_object_for_this_type(pk=self._original_assigned_object_id)
             original_parent = getattr(original_assigned_object, 'parent_object', None)