Add a dedicated RQ queue for exports.

Refs https://redmine.teklia.com/issues/5584

The export tasks should run on a dedicated RQ queue so we can separate them from other tasks in production to run on servers with large HDDs

arkindex/users/tests/test_jobs.py

@@ -222,6 +222,7 @@ class TestJobs(FixtureAPITestCase):
         self.assertEqual(get_queue_mock.call_args_list, [
             call("default"),
             call("high"),
+            call("export"),
         ])
 
         # Called once per queue
@@ -291,6 +292,7 @@ class TestJobs(FixtureAPITestCase):
         self.assertEqual(get_queue_mock.call_args_list, [
             call("default"),
             call("high"),
+            call("export"),
         ])
 
         self.assertListEqual(get_queue_mock().fetch_job.call_args_list, [