[3.4] Completion for PHP-based configuration for services

[Haehnchen]

// app/config/services.php
return function (ContainerConfigurator $container) {
    $container->import('legacy_services.php');

    $params = $container->parameters();
    $params->set('app.foo_param', 'param_value');

    $container = $container->services()->defaults()
        ->private()
        ->autoconfigure()
        ->autowire();

    $container
        ->load('App\\', '../src/*')
        ->exclude('../src/{Entity,Repository,Tests}');
    $container
        ->load('App\\Controller\\', '../src/Controller')
        ->tag('controller.service_arguments');

    $container->set(FooClass::class)
        ->args(['some_argument', ref(BarClass::class)])
        ->tag('kernel.event_listener', ['event' => 'kernel.exception']);

    $container->alias('foo', FooClass::class)->public();
};

https://symfony.com/blog/new-in-symfony-3-4-php-based-configuration-for-services-and-routes

symfony/symfony#23834