With the implementation of PAGES-933, we do not have to wait for a page to be rendered in order for the edit page properties to be shown. By not relying on the client side to provide the dialog id, the page prototype (from the site module) is not taken into consideration.
At the writing time of this issue, the site-app is not bundled into the saas instance, therefore there is no page prototype. When the site prototype is going to be available, we need to integrate with the module in order to present to the user the merged dialog (page dialog + prototype dialog) in order for the complete property set to be editable.

AC: 
  integrate pages app with the site module

  read the prototype page template from the site module, and if available, apply the changes to the edit page property action and action availability