migration symfony 5 4 (#300)

* symfony 5.4 (diff dev)

* symfony 5.4 (working)

* symfony 5.4 (update autoload)

* symfony 5.4 (remove swiftmailer mailer implementation)

* symfony 5.4 (php doc and split Global accessor class)


### Impacted packages:

composer require php:">=7.2.5 <8.0.0" symfony/console:5.4.* symfony/dotenv:5.4.* symfony/framework-bundle:5.4.* symfony/twig-bundle:5.4.* symfony/yaml:5.4.* --update-with-dependencies

composer require symfony/stopwatch:5.4.* symfony/web-profiler-bundle:5.4.* --dev --update-with-dependencies

lib/symfony/framework-bundle/DependencyInjection/Compiler/TestServiceContainerRealRefPass.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class TestServiceContainerRealRefPass implements CompilerPassInterface
+{
+    public function process(ContainerBuilder $container)
+    {
+        if (!$container->hasDefinition('test.private_services_locator')) {
+            return;
+        }
+
+        $privateContainer = $container->getDefinition('test.private_services_locator');
+        $definitions = $container->getDefinitions();
+        $privateServices = $privateContainer->getArgument(0);
+
+        foreach ($privateServices as $id => $argument) {
+            if (isset($definitions[$target = (string) $argument->getValues()[0]])) {
+                $argument->setValues([new Reference($target)]);
+            } else {
+                unset($privateServices[$id]);
+            }
+        }
+
+        $privateContainer->replaceArgument(0, $privateServices);
+    }
+}