Switch from XML-based to PHP-based service configuration

XML-based service configuration has been deprecated since symfony/symfony#60568 and will no longer be supported in Symfony 8.0.

See also https://symfony.com/blog/new-in-symfony-7-4-deprecated-xml-configuration.

In order for ComposerRequireChecker to recognise where the functions come from, we have to import them explicitly. At the same time, PHP-CS-Fixer must not remove the import, which is actually superfluous.

X-Ref GromNaN/symfony-config-xml-to-php#29, maglnet/ComposerRequireChecker#193 (comment)

Author: mpdude

src/NotModified/services.xml

@@ -0,0 +1,17 @@
+<?php
+
+namespace Symfony\Component\DependencyInjection\Loader\Configurator;
+
+return static function(ContainerConfigurator $container) {
+    $services = $container->services();
+    $parameters = $container->parameters();
+
+    $services->set(\Webfactory\HttpCacheBundle\NotModified\EventListener::class, \Webfactory\HttpCacheBundle\NotModified\EventListener::class)
+        ->public()
+        ->args([
+            service('service_container'),
+            '%kernel.debug%',
+        ])
+        ->tag('kernel.event_listener', ['event' => 'kernel.controller', 'priority' => -200])
+        ->tag('kernel.event_listener', ['event' => 'kernel.response']);
+};