Performance: Fit video to frame without polling RTP stats

It turns out that the timers which repeatedly poll the RTP stats of each video track all run independently of each other and can add up to a small but constant sink of CPU. Meanwhile we can replace these timers with HTMLVideoElement 'resize' event listeners, which is way more efficient and reacts instantly to orientation changes.

src/state/media/observeRtpStreamStats.ts

@@ -69,12 +69,3 @@ export function observeInboundRtpStreamStats$(
     map((x) => x as RTCInboundRtpStreamStats | undefined),
   );
 }
-
-export function observeOutboundRtpStreamStats$(
-  participant: Participant,
-  source: Track.Source,
-): Observable<RTCOutboundRtpStreamStats | undefined> {
-  return observeRtpStreamStats$(participant, source, "outbound-rtp").pipe(
-    map((x) => x as RTCOutboundRtpStreamStats | undefined),
-  );
-}