Use pluralized translation for delete success toast

aleksis/core/frontend/components/generic/dialogs/DeleteMultipleDialog.vue

@@ -159,7 +159,7 @@ export default {
     deleteSuccessMessageI18nKey: {
       type: String,
       required: false,
-      default: "status.object_delete_success",
+      default: "status.objects_delete_success",
     },
   },
 };

aleksis/core/frontend/messages/en.json

@@ -263,7 +263,8 @@
     "updating": "Changes are being synced.",
     "object_create_success": "The object was created successfully.",
     "object_edit_success": "The object was edited successfully.",
-    "object_delete_success": "The object was deleted successfully."
+    "object_delete_success": "The object was deleted successfully.",
+    "objects_delete_success": "The objects were deleted successfully."
   },
   "rooms": {
     "menu_title": "Rooms",