Closes #9623: Implement saved filters (#10801)

* Initial work on saved filters

* Return only enabled/shared filters

* Add tests

* Clean up filtering of usable SavedFilters

netbox/extras/forms/__init__.py

@@ -2,6 +2,6 @@ from .model_forms import *
 from .filtersets import *
 from .bulk_edit import *
 from .bulk_import import *
-from .customfields import *
+from .mixins import *
 from .config import *
 from .scripts import *