fix(iOS15) fix not being able to unmute if "everyone starts muted" is set

We need to make sure the audio track is added to the JVB connection, or we won't
be able to unmute.

Why this happens is a mystery wrapped in an enigma, it started happening with
iOS 15.

Same thing applies to Safari for macOS.

Fixes: https://github.com/jitsi/jitsi-meet/issues/10104

JitsiConference.js

  * @returns {Array<JitsiLocalTrack>} - list of local tracks that are unmuted.
  */
 JitsiConference.prototype._getInitialLocalTracks = function() {
-    // Always add the audio track on mobile Safari because of a known issue where audio playout doesn't happen
-    // if the user joins audio and video muted.
+    // Always add the audio track on certain platforms:
+    //  * Safari / WebKit: because of a known issue where audio playout doesn't happen
+    //    if the user joins audio and video muted.
+    //  * React Native: after iOS 15, if a user joins muted they won't be able to unmute.
     return this.getLocalTracks()
-        .filter(track => (track.getType() === MediaType.AUDIO && (!this.isStartAudioMuted() || browser.isIosBrowser()))
-        || (track.getType() === MediaType.VIDEO && !this.isStartVideoMuted()));
+        .filter(track => {
+            const trackType = track.getType();
+
+            if (trackType === MediaType.AUDIO
+                    && (!this.isStartAudioMuted() || browser.isWebKitBased() || browser.isReactNative())) {
+                return true;
+            } else if (trackType === MediaType.VIDEO && !this.isStartVideoMuted()) {
+                return true;
+            }
+
+            return false;
+        });
 };
 
 /**