Closes #13427: Public model registration (#14152)

* Initial work on #13427

* Clarify documentation

* Reference public models registry when populating models for ConfigTemplate context

netbox/core/migrations/0008_contenttype_proxy.py

@@ -0,0 +1,29 @@
+# Generated by Django 4.2.6 on 2023-10-31 19:38
+
+import core.models.contenttypes
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contenttypes', '0002_remove_content_type_name'),
+        ('core', '0007_job_add_error_field'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ContentType',
+            fields=[
+            ],
+            options={
+                'proxy': True,
+                'indexes': [],
+                'constraints': [],
+            },
+            bases=('contenttypes.contenttype',),
+            managers=[
+                ('objects', core.models.contenttypes.ContentTypeManager()),
+            ],
+        ),
+    ]