message: feat: add 'extra' column to saved_queries GET
  This column contains schedule information when the feature flag
  `SCHEDULED_QUERIES` is enabled. Adding it here makes it available
  through the REST API.
diff: @@ -98,6 +98,7 @@ class SavedQueryRestApi(BaseSupersetModelRestApi):
  "sql_tables",
  "rows",
  "last_run_delta_humanized",
  + "extra",
  ]
  add_columns = ["db_id", "description", "label", "schema", "sql"]
  edit_columns = add_columns
  