saveSnapshot method
Stores snapshot as the latest roomId snapshot and deletes the log
entries it covers (sequence number <= RelaySnapshotRecord.upToSeq).
Implementation
@override
Future<void> saveSnapshot(
String roomId,
RelaySnapshotRecord snapshot,
) async {
final room = _room(roomId)..snapshot = snapshot;
room.log.removeWhere((entry) => entry.seq <= snapshot.upToSeq);
}