Adding bulk deletion endpoint for notifications (#3154)

* Catch DoesNotExist error

* Move notificationtable function to js file

* Fix for custom metadata class

- Previously only worked if a POST or PUT action was available on the endpoint
- So, a ListAPIView endpoint would not actually work!
- Adding in a BulkDelete mixin to a ListAPIView caused failure

* Add unit test to ensure new OPTIONS metadata updates are checked

* Expand functionality of the existing BulkDelete mixin

- Allow deletion by custom filters
- Allow each implementing class to implement custom filters
- Adds more unit testing for BulkDelete mixin class

* Add bulk delete operation for Notification API

- Ensure users can only delete their *own* notifications

* Improve notification tables / buttons / etc

* Adds unit testing for bulk delete of notifications

- Fixed API permissions for notifications list endpoint

* Update BulkDelete operations for the StockItemTestResult table

* Use filters parameter in attachments table to ensure that only correct attachments are deleted

* JS linting

* Fixes for unit tests

InvenTree/users/fixtures/users.yaml

@@ -36,6 +36,7 @@
     first_name: "Alan"
     last_name: "Allgroup"
     is_active: false
+    is_staff: true
     groups:
       - 1
       - 2