Closes #14436: Add indexes for all GenericForeignKey fields (#14463)

* Closes #14436: Add PostgreSQL indexes for all GenericForeignKeys

* Add note about GFK indexes to developer docs

netbox/dcim/migrations/0184_gfk_indexes.py

@@ -0,0 +1,25 @@
+# Generated by Django 4.2.7 on 2023-12-07 16:09
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('dcim', '0183_protect_child_interfaces'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='cabletermination',
+            index=models.Index(fields=['termination_type', 'termination_id'], name='dcim_cablet_termina_884752_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='inventoryitem',
+            index=models.Index(fields=['component_type', 'component_id'], name='dcim_invent_compone_0560bb_idx'),
+        ),
+        migrations.AddIndex(
+            model_name='inventoryitemtemplate',
+            index=models.Index(fields=['component_type', 'component_id'], name='dcim_invent_compone_77b5f8_idx'),
+        ),
+    ]