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/Session/DeprecatedSessionFactory.php

@@ -0,0 +1,46 @@
+<?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\Session;
+
+use Symfony\Component\HttpFoundation\Exception\SessionNotFoundException;
+use Symfony\Component\HttpFoundation\RequestStack;
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
+
+/**
+ * Provides session and trigger deprecation.
+ *
+ * Used by service that should trigger deprecation when accessed by the user.
+ *
+ * @author Jérémy Derussé <jeremy@derusse.com>
+ *
+ * @internal to be removed in 6.0
+ */
+class DeprecatedSessionFactory
+{
+    private $requestStack;
+
+    public function __construct(RequestStack $requestStack)
+    {
+        $this->requestStack = $requestStack;
+    }
+
+    public function getSession(): ?SessionInterface
+    {
+        trigger_deprecation('symfony/framework-bundle', '5.3', 'The "session" service and "SessionInterface" alias are deprecated, use "$requestStack->getSession()" instead.');
+
+        try {
+            return $this->requestStack->getSession();
+        } catch (SessionNotFoundException $e) {
+            return null;
+        }
+    }
+}