Todo: restore user overrides when a user leaves and rejoins the server

[FloatingMilkshake]

Discord does not preserve user overrides after the user has left & rejoined, so if we want to have this be automatic we'll need to have Cliptok store user overrides when they are set (but it will also need to acquire all of them when this is implemented) and then, when a user joins the server, if they had an override set previously, it should be re-applied.