feat: web push notification when someone enters the lobby

[acollign]

This PR implements #7518 which consists of notifying players when someone enters the lobby.

[NoahTheDuke]

This isn't correct, I'm sorry to say:

1. .requestPermission is a promise, so calling it without a .then won't actually wait to get permission.
2. This doesn't handle if the browser doesn't support notifications, so it'll fail and not play any sounds in that case.
3. It doesn't support if the user rejects the permissions request.
4. In Safari and Firefox, .requestPermissions can only be called in a user event, like clicking. So you'd need to move the permissions check to something like the create-game and/or join-game callbacks.
5. This will pop a notification if someone joins your game or if you join someone else's game because we fire :lobby/notification in both cases. I don't think it's good UX to get a notification when deliberately clicking on a game. You'll need to figure out a way to only alert the user when someone else joins the game.

[acollign]

This isn't correct, I'm sorry to say:

No problem @NoahTheDuke. Thank you very much for your feedback. I will work on a different solution.