feat: allow custom RTCPeerConnection config

[hanifanazka]

Allow custom RTCPeerConnection configuration. This is inspired of myown need to switch encodedInsertableStreams true to cater WebRTC Insertable Streams.

This edit hasn't thoroughly tested, so advices are welcomed. Alternatively, this workaround found successful in my test:

const OriginalRTCPeerConnection = window.RTCPeerConnection;
window.RTCPeerConnection = function (config: any) {
  // Force the flag into every new connection
  const newConfig = { ...config, encodedInsertableStreams: true };
  return new OriginalRTCPeerConnection(newConfig);
} as any;

const webrtcPlayer = new WebRTCPlayer({
  video: videoRef.current,
  type: 'whep',
});

window.RTCPeerConnection = OriginalRTCPeerConnection;