Add logging to diagnose no-video bug (#7721)

Log in/outbound RTP stats so we can see ifn we're sending & receiving
video, and log when we successfully play the video element.

src/CallHandler.tsx

@@ -643,6 +643,16 @@ export default class CallHandler extends EventEmitter {
                 `bytes received: ${pair.bytesReceived}, bytes sent: ${pair.bytesSent}, `,
             );
         }
+
+        logger.debug("Outbound RTP:");
+        for (const s of stats.filter(item => item.type === 'outbound-rtp')) {
+            logger.debug(s);
+        }
+
+        logger.debug("Inbound RTP:");
+        for (const s of stats.filter(item => item.type === 'inbound-rtp')) {
+            logger.debug(s);
+        }
     }
 
     private setCallState(call: MatrixCall, status: CallState): void {

src/components/views/voip/VideoFeed.tsx

@@ -137,6 +137,7 @@ export default class VideoFeed extends React.PureComponent<IProps, IState> {
             // them with another load() which will cancel the pending one, but since we don't call
             // load() explicitly, it shouldn't be a problem. - Dave
             await element.play();
+            logger.debug((this.props.feed.isLocal ? "Local" : "Remote") + " video feed play() completed");
         } catch (e) {
             logger.info("Failed to play media element with feed", this.props.feed, e);
         }