Feature: #89700 - Show layouts in the Web Info module

See Issue #89700

Description

It’s now possible to get an overview of the configured backend and frontend layouts of a page in the Web->Info module. Therefore a new entry “Layouts” is available for the page tree overview.

Besides the “Backend Layout (this page only)”, the “Backend Layout (subpages of this page)” and the “Layout” fields, which do all just display the title of the current field value, an additional field “Actual backend layout” is displayed. This field contains the title of the backend layout, which is actually used for the page. If set, this is the same as “Backend Layout (this page only)”. Otherwise, it contains the inherited layout from a parent page, which defined “Backend Layout (subpages of this page)”.

This is especially useful for editors to determine the actually used backend layout, which was previously often difficult. For example in installations with large page trees and highly developed inheritance.

In case the current field value is invalid, e.g. referencing a non-existent backend layout, this is now also shown to the editor.

Impact

The Web->Info module now contains a new page tree overview type, which contains the layout related fields as well as an additional field, displaying the actually used backend layout for the corresponding page.