Feature: #99055 - BackendController service tag attribute

See forge#99055

Description

A new PHP attribute TYPO3\CMS\Backend\Attribute\Controller has been added in order to register services to the BackendController dependency injection container.

In addition to tag backend.controller in the Services.yaml file, tagging services as backend controller can be done like:

Example implementation

use TYPO3\CMS\Backend\Attribute\Controller;

#[Controller]
class MyBackendController {

}

Impact

It is now possible to tag services as backend controller by the PHP attribute TYPO3\CMS\Backend\Attribute\Controller instead of tagging them with backend.controller in the Services.yaml file.