Feature: #104935 - Allow moving content elements via page tree

Description

To make managing content across pages easier, a backend user may now drag content elements from the Web > Page module into a page in the page tree.

Once dropped, a modal window opens, allowing the backend user to select the position for placing the content element and to change the target page if needed.

Impact

Content elements can be moved from the Web > Page module into the page tree to initiate the moving process.