Make filter a bit more consistent accross UI

Add `description`, `created_by` and `modified_by` when those fields are
available.

See: https://github.com/ansible/awx/issues/7410

awx/ui_next/src/screens/NotificationTemplate/NotificationTemplateList/NotificationTemplateList.jsx

@@ -104,6 +104,10 @@ function NotificationTemplatesList({ i18n }) {
                 key: 'name',
                 isDefault: true,
               },
+              {
+                name: i18n._(t`Description`),
+                key: 'description__icontains',
+              },
               {
                 name: i18n._(t`Type`),
                 key: 'notification_type',