Routing config in PHP

[willemverspyck]

Subject

I am targeting this branch, because it's BC.

Symfony is making XML routing configs deprecated, so I think it's a good to start to add the PHP config for routings in SonataAdminBundle. To prevent duplicate configs, I imported the PHP config from the XML config and made the XML config deprecated. The minimum required Symfony version for Sonata is 6.4, so PHP configs are fully supported.

Changes are based on symfony/symfony#60232

Changelog

### Added

### Changed
- Converted the XML of the routing to PHP

### Deprecated
- Using XML config

### Removed

### Fixed

### Security