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/event-dispatcher/DependencyInjection/AddEventAliasesPass.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\Component\EventDispatcher\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * This pass allows bundles to extend the list of event aliases.
+ *
+ * @author Alexander M. Turek <me@derrabus.de>
+ */
+class AddEventAliasesPass implements CompilerPassInterface
+{
+    private $eventAliases;
+    private $eventAliasesParameter;
+
+    public function __construct(array $eventAliases, string $eventAliasesParameter = 'event_dispatcher.event_aliases')
+    {
+        if (1 < \func_num_args()) {
+            trigger_deprecation('symfony/event-dispatcher', '5.3', 'Configuring "%s" is deprecated.', __CLASS__);
+        }
+
+        $this->eventAliases = $eventAliases;
+        $this->eventAliasesParameter = $eventAliasesParameter;
+    }
+
+    public function process(ContainerBuilder $container): void
+    {
+        $eventAliases = $container->hasParameter($this->eventAliasesParameter) ? $container->getParameter($this->eventAliasesParameter) : [];
+
+        $container->setParameter(
+            $this->eventAliasesParameter,
+            array_merge($eventAliases, $this->eventAliases)
+        );
+    }
+}