Use the same registration open/close menu in pairings and players screens

[haradan]

Currently when you go to start the first round, there's a button next to it to remind you to close registration, or in case you wanted to reopen it. We also show a confirmation dialog to the TO if they try to pair a new round when registration is open or a player's deck is unlocked.

It would be nice to make the button to open/close/lock/unlock registration look the same on both the players screen and the rounds/pairings screen. The way it looks and works on the players screen now can be applied to the rounds/pairings screen as well.

We can still highlight it in a different colour if the registration is open and unlocked, to prompt the TO to close registration before the first round.