Fix FS-11874

Verto JS libs allow passing an attachStreams array of MediaStream objects, which are then supposed to be added to the peer connection in the order they are supplied in the array.

However, there is a faulty logic check prior to actually adding the streams, where 'options.attachStream' is checked for length instead of 'options.attachStreams'.

html5/verto/js/src/jquery.FSRTC.js

@@ -778,7 +778,7 @@
         // attachStreams[0] = audio-stream;
         // attachStreams[1] = video-stream;
         // attachStreams[2] = screen-capturing-stream;
-        if (options.attachStreams && options.attachStream.length) {
+        if (options.attachStreams && options.attachStreams.length) {
             var streams = options.attachStreams;
             for (var i = 0; i < streams.length; i++) {
                 peer.addStream(streams[i]);