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/Loader/Configurator/Traits/ClassTrait.php

@@ -11,19 +11,14 @@
 
 namespace Symfony\Component\DependencyInjection\Loader\Configurator\Traits;
 
-/**
- * @method $this class(string $class)
- */
 trait ClassTrait
 {
     /**
      * Sets the service class.
      *
-     * @param string $class The service class
-     *
      * @return $this
      */
-    final protected function setClass($class)
+    final public function class(?string $class): self
     {
         $this->definition->setClass($class);