get https://example.com/delivery/v1/sites//pages/by-parent/
Returns the descriptors of all public child pages which are direct children of the parent page that is specified by parentPageId. The page is a member of the site that is specified in siteId.
If the value of parentPageId is @top, then the descriptors of the top-level pages are returned.
User roles: admin, manager, editor, viewer, authenticatedVisitor, anonymous