organize entry point jsx for admin pages

src/client/js/admin.jsx

@@ -28,6 +28,8 @@ import AdminMarkDownContainer from './services/AdminMarkDownContainer';
 import AdminExternalAccountsContainer from './services/AdminExternalAccountsContainer';
 import AdminNotificationContainer from './services/AdminNotificationContainer';
 
+import './app';
+
 const logger = loggerFactory('growi:admin');
 
 const appContainer = window.appContainer;

src/server/views/layout/admin.html

@@ -4,9 +4,8 @@
 {% block html_base_css %}admin-page{% endblock %}
 
 
-{% block html_additional_headers %}
-  {% parent %}
-  <script src="{{ webpack_asset('js/admin.js') }}" defer></script>
+{% block html_head_loading_app %}
+<script src="{{ webpack_asset('js/admin.js') }}" defer></script>
 {% endblock %}
 
 {# disable custom script in admin page #}