Function headless_lms_models::library::regrading::regrade

pub async fn regrade(
    conn: &mut PgConnection,
    exercise_services_by_type: &HashMap<String, (ExerciseService, ExerciseServiceInfo)>,
    send_grading_request: impl Fn(Url, &ExerciseTask, &ExerciseTaskSubmission) -> BoxFuture<'static, ModelResult<ExerciseTaskGradingResult>>
) -> ModelResult<()>