title: Convert String to UTF-16 Byte Array in GJS
body: <p>In my Gnome Extension I would like to call <code>GLib.convert</code>. Sadly it does not work with strings but wants a ByteArray. Now I wonder how to convert a Javascript String into a UTF-16 Byte Array.</p>
  <p>Bonus points if this uses some part of the Gnome bindings instead of implementing in Javascript.</p>