Closes #12988: Introduce custom field choice sets (#13195)

* Initial work on custom field choice sets

* Rename choices to extra_choices (prep for #12194)

* Remove CustomField.choices

* Add & update tests

* Clean up table columns

* Add order_alphanetically boolean for choice sets

* Introduce ArrayColumn for choice lists

* Show dependent custom fields on choice set view

* Update custom fields documentation

* Introduce ArrayWidget for more convenient editing of choices

* Incorporate PR feedback

* Misc cleanup

netbox/extras/api/views.py

@@ -1,6 +1,5 @@
 from django.contrib.contenttypes.models import ContentType
 from django.http import Http404
-from django.shortcuts import get_object_or_404
 from django_rq.queues import get_connection
 from rest_framework import status
 from rest_framework.decorators import action
@@ -55,11 +54,17 @@ class WebhookViewSet(NetBoxModelViewSet):
 
 class CustomFieldViewSet(NetBoxModelViewSet):
     metadata_class = ContentTypeMetadata
-    queryset = CustomField.objects.all()
+    queryset = CustomField.objects.select_related('choice_set')
     serializer_class = serializers.CustomFieldSerializer
     filterset_class = filtersets.CustomFieldFilterSet
 
 
+class CustomFieldChoiceSetViewSet(NetBoxModelViewSet):
+    queryset = CustomFieldChoiceSet.objects.all()
+    serializer_class = serializers.CustomFieldChoiceSetSerializer
+    filterset_class = filtersets.CustomFieldChoiceSetFilterSet
+
+
 #
 # Custom links
 #