Adding support for decorating messenger handlers

[yceruto]

When symfony/messenger component is installed, you can use any decorator around the message handler:

namespace App\Handler;

use Yceruto\DecoratorBundle\Decorator\Doctrine\ORM\Transactional;

#[AsMessageHandler]
class ProductCreatedEventHandler
{
    #[Transactional]
    public function __invoke(ProductCreatedEvent $event): void
    {
        // update other related information...
    }
}