Expose ExperiencePage state through Component and XPage Resource backend calls

The backend REST calls of ComponentResource and XpageResource return the list of current actions available for channel, page and xpages. This call should also expose the state of (at least) the xpage so it can be used to render the notification header.

This document describes all the different properties required: https://docs.google.com/spreadsheets/d/1GOq_-dztjLmQ6MMpsJoEF6hg8eDFLTrlAKcQgTtLe50/edit?usp=sharing