Add settings to the devel configuration page

That would make the module more user friendly for sure, but I wouldn't know where we would assign the config value to \Kint::$depth_limit. It would need to happen as early as possible so that any place where users use Kint, the $depth_limit is already changed. We could try to do it in a middleware, but one that runs at a time where the config factory is already accessible.

This is not something I'm going to work on anytime soon, but I'm happy to help/review if anyone else wants to give this a go.