Users without edit permissions can be set as editors for a page

In the Permissions tab of a page, when you use the "These Users can Edit" field to add editors for the page, you have the option to add any user. That includes users who only have `guest` permissions. Only users with the ability to edit a page/piece should be available to add as editors.

Start in the Permissions tab implementation and trace how the “These Users can Edit” field filters users by permission. Done means guest-only users cannot be selected, while users who can edit a page or piece remain available; verify the page editor flow.

Written by the indexing model from the issue text.