Don't update local currentTime state unnecessarily

[JoshuaKGoldberg]

Following #9: right now, useTimeSynchronization updates both the local roomData.currentTime and the server state:

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

Lines 16 to 20 in 6c26f5c

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

Nothing in local UI should actually subscribes to currentTime... and even if we do add something that does, we already receive updates from the server whenever currentTime or any other room data updates.

Proposal: as a performance improvement, emit the new currentTime to the server directly, without also setting it in React state.