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/polyfill-php80/Resources/stubs/PhpToken.php

@@ -0,0 +1,7 @@
+<?php
+
+if (\PHP_VERSION_ID < 80000 && \extension_loaded('tokenizer')) {
+    class PhpToken extends Symfony\Polyfill\Php80\PhpToken
+    {
+    }
+}