On demand notifications, routing logic in notification class

[x7ryan]

I find I need to do a lot of on demand notifications (not tied to a notifiable entity). This can be done though the Notification facade passing in a route method (https://laravel.com/docs/8.x/notifications#on-demand-notifications). However that would require me to define routing everywhere I dispatch a notification.

I was thinking it would be nice to be able to put that routing logic in the notification class itself and just call Notification::notify(new SomeNotification($data));. I would use this a lot for slack messages to myself when certain events happen in app. There is only ever one way to route that and so I would like to be able to add a method to the notification to define that like:

public function routeSlack()
{
return 'https://hooks.slack.com/...';
}

I haven't looked deep into how Laravel's notifications work but I'd be open to looking into it and making a PR to do this if its something others agree would make sense, or maybe I just have a unique use-case. I am thinking if you define a route() method when calling the notification it would use that, but if not it would look for something like a "route(Driver)" method inside the notification class.

On that same note, I was also thinking of adding a global notification helper so I could just call notify(new SomeNotification($data)); instead of importing the notification facade and calling Notification::notify(new SomeNotification($data));. Assuming that's not going to cause any naming collisions.

Interested in feedback if this would be worth my time to put up a PR for.