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/yaml/Resources/bin/yaml-lint

@@ -0,0 +1,45 @@
+#!/usr/bin/env php
+<?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.
+ */
+
+/**
+ * Runs the Yaml lint command.
+ *
+ * @author Jan Schädlich <jan.schaedlich@sensiolabs.de>
+ */
+
+use Symfony\Component\Console\Application;
+use Symfony\Component\Yaml\Command\LintCommand;
+
+function includeIfExists(string $file): bool
+{
+    return file_exists($file) && include $file;
+}
+
+if (
+    !includeIfExists(__DIR__ . '/../../../../autoload.php') &&
+    !includeIfExists(__DIR__ . '/../../vendor/autoload.php') &&
+    !includeIfExists(__DIR__ . '/../../../../../../vendor/autoload.php')
+) {
+    fwrite(STDERR, 'Install dependencies using Composer.'.PHP_EOL);
+    exit(1);
+}
+
+if (!class_exists(Application::class)) {
+    fwrite(STDERR, 'You need the "symfony/console" component in order to run the Yaml linter.'.PHP_EOL);
+    exit(1);
+}
+
+(new Application())->add($command = new LintCommand())
+    ->getApplication()
+    ->setDefaultCommand($command->getName(), true)
+    ->run()
+;