Adjust total number of players before the game starts

[TylerYep]

Love playing Hanabi on this website, thanks for maintaining this game!

One really annoying behavior I run into a lot is that the total number of players is fixed before the game begins.

For example, I might create a game for 4 people and 1 person will drop out, causing us to need to create an entirely new game and send a new link. Or, one player might ask to join late while we're waiting in the lobby and we'll need to create a new game and send a new link again.

Ideally, we shouldn't need to select the number of players before creating the link - it should just be the number of players waiting in the game before "Start Game" is clicked.

I think this will make it much easier to adjust the number of players when organizing games.

Thanks!