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/AbstractArgument.php

@@ -0,0 +1,41 @@
+<?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;
+
+/**
+ * Represents an abstract service argument, which have to be set by a compiler pass or a DI extension.
+ */
+final class AbstractArgument
+{
+    private $text;
+    private $context;
+
+    public function __construct(string $text = '')
+    {
+        $this->text = trim($text, '. ');
+    }
+
+    public function setContext(string $context): void
+    {
+        $this->context = $context.' is abstract'.('' === $this->text ? '' : ': ');
+    }
+
+    public function getText(): string
+    {
+        return $this->text;
+    }
+
+    public function getTextWithContext(): string
+    {
+        return $this->context.$this->text.'.';
+    }
+}