Feature: #96152 - Backend Toolbar items overview in configuration module

See Issue #96152

Description

With Issue #96041, the registration of backend toolbar items had been improved. Instead of being registered via $GLOBALS, all implementations of ToolbarItemsInterface are now automatically registered, while taking the defined index into account.

To still allow administrators an overview of the registered toolbar items, especially the final ordering, a corresponding list has been added to the configuration module.

Impact

It’s now possible for administrators to get an overview of all registered toolbar items and the final ordering in the configuration module.