feat(embed-meeting) add autoplay permission to iframe sample

react/features/embed-meeting/components/EmbedMeetingDialog.js

      * @returns {string} The iframe embed code.
      */
     const getEmbedCode = () =>
-        `<iframe allow="camera; microphone; fullscreen; display-capture" src="${url}"`
+        `<iframe allow="camera; microphone; fullscreen; display-capture; autoplay" src="${url}"`
         + ' style="height: 100%; width: 100%; border: 0px;"></iframe>';
 
     return (