Extract component for account/admin menu links

This way we remove the duplication in the layouts which had these links.

Since we're now passing the `current_user` option to partials in all
cases, IMHO the code is easier to follow if we use the
`Layout::NotificationItemComponent` instead of its partial.

app/components/layout/admin_header_component.html.erb

@@ -28,11 +28,7 @@
       <% if show_admin_menu?(user) || namespace != "management" %>
         <div id="responsive_menu">
           <div class="top-bar-right">
-            <ul class="menu" data-responsive-menu="medium-dropdown">
-              <%= render "shared/admin_login_items", current_user: user %>
-              <%= render "layouts/notification_item", current_user: user %>
-              <%= render "devise/menu/login_items", current_user: user %>
-            </ul>
+            <%= render Layout::AccountMenuComponent.new(user) %>
           </div>
         </div>
       <% end %>