Move services code brought in from Mojo to live under //third_party.

third_party/mojo_services/src/public/sky/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 action_foreach("sky") {
   script = "../../../public/sky/convert_amd_modules_to_sky.py"
   sources = [
     "../js/application.js",
     "../js/service_provider.js",
     "../js/shell.js",
   ]
   outputs = [
     "$target_gen_dir/{{source_name_part}}.sky",
   ]
   args = [
     "--input",
     "{{source}}",
     "--output",
     rebase_path(target_gen_dir, root_build_dir) + "/{{source_name_part}}.sky",
   ]
 }