Clients should not broadcast currentTime updates when they are not the player

[JoshuaKGoldberg]

Following #9: right now, useTimeSynchronization always sends video time updates to the server, no matter what:

karaokenite-react/src/pages/room/RoomEvents/useVideoControls/useTimeSynchronization.ts

Lines 16 to 20 in 6c26f5c

	useInterval(() => {
	emitRoomData({
	currentTime: videoElement.currentTime,
	});
	}, videoElementSyncInterval);

However, the server only cares about updates from room.player:

karaokenite-react/src/server/events/karaoke.ts

Lines 42 to 48 in ae0b71a

	// Ignore currentTime updates from any client who didn't click the play button.
	// This is a somewhat arbitrary measure to stop "currentTime battles", wherein
	// two clients go back and forth sending vastly different times to each other.
	currentTime:
	newPlayer === person.id
	? data.currentTime ?? room.data.currentTime
	: room.data.currentTime,

It's a waste of bandwidth for the client to constantly be sending currentTime updates if they've received a notice of room data from the server that includes someone else's ID as the player. Since the server (once #13 is resolved) informs clients there is no more player when the player leaves, clients would start broadcasting their time again when needed.

Proposal: a client should only broadcast its currentTime if its ID matches the room data's player.

Sub-proposal: once this and #13 are in, make the frequency of currentTime updates something like 100 instead of the current 500, to take advantage of the reduced spam sent to the server.

(Blocked on #13 being resolved)