Fix talking collision not colliding properly

The code was only entering the blocked state if the user was speaking,
which often won't be the case when another person starts speaking because
we'll have pressed the button but not got the ack back from the server
yet. Add the transmitblocked flag instead so we don't enter that state
again if we've already decided we've been blocked.

We were also starting with blocked = false and so resetting it when it
shouldn't have been reset.

Also requires matrix-org/matrix-js-sdk#2502

src/room/usePTT.ts

@@ -130,7 +130,7 @@ export const usePTT = (
   const onMuteStateChanged = useCallback(() => {
     const activeSpeakerFeed = getActiveSpeakerFeed(userMediaFeeds, groupCall);
 
-    let blocked = false;
+    let blocked = transmitBlocked;
     if (activeSpeakerUserId === null && activeSpeakerFeed !== null) {
       if (activeSpeakerFeed.userId === client.getUserId()) {
         playClip(PTTClipID.START_TALKING_LOCAL);
@@ -141,8 +141,8 @@ export const usePTT = (
       playClip(PTTClipID.END_TALKING);
     } else if (
       pttButtonHeld &&
-      activeSpeakerUserId === client.getUserId() &&
-      activeSpeakerFeed?.userId !== client.getUserId()
+      activeSpeakerFeed?.userId !== client.getUserId() &&
+      !transmitBlocked
     ) {
       // We were talking but we've been cut off: mute our own mic
       // (this is the easier way of cutting other speakers off if an
@@ -167,6 +167,7 @@ export const usePTT = (
     client,
     userMediaFeeds,
     setMicMuteWrapper,
+    transmitBlocked,
   ]);
 
   useEffect(() => {