Allow users with edit rights on a page and all its children to use the Pinned Pages feature

At this point, users must have :

• space admin rights on the parent page in order to manipulate the order of the child pages
• wiki admin rights in order to manipulate the order of top level pages

This is an important restriction, limiting too much the usage of this feature.
In the majority of cases, users with edit rights on the page and on all their children should be able to manipulate the pinned pages.