Function move_task_submissions_grades 

pub fn move_task_submissions_grades<T: MedalConnection>(
    conn: &T,
    session_token: &str,
    csrf_token: &str,
    old_location: &str,
    new_location: &str,
    old_contest: &str,
    new_contest: &str,
) -> Result<Map<String, Value>, MedalError>