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/dependency-injection/Argument/ServiceLocatorArgument.php

@@ -0,0 +1,44 @@
+<?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\Component\DependencyInjection\Argument;
+
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * Represents a closure acting as a service locator.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class ServiceLocatorArgument implements ArgumentInterface
+{
+    use ReferenceSetArgumentTrait;
+
+    private $taggedIteratorArgument;
+
+    /**
+     * @param Reference[]|TaggedIteratorArgument $values
+     */
+    public function __construct($values = [])
+    {
+        if ($values instanceof TaggedIteratorArgument) {
+            $this->taggedIteratorArgument = $values;
+            $this->values = [];
+        } else {
+            $this->setValues($values);
+        }
+    }
+
+    public function getTaggedIteratorArgument(): ?TaggedIteratorArgument
+    {
+        return $this->taggedIteratorArgument;
+    }
+}