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/web-profiler-bundle/Resources/views/Icon/mailer.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24"><path fill="#AAAAAA" d="M22,4.9C22,3.9,21.1,3,20.1,3H3.9C2.9,3,2,3.9,2,4.9v13.1C2,19.1,2.9,20,3.9,20h16.1c1.1,0,1.9-0.9,1.9-1.9V4.9z M8.3,14.1l-3.1,3.1c-0.2,0.2-0.5,0.3-0.7,0.3S4,17.4,3.8,17.2c-0.4-0.4-0.4-1,0-1.4l3.1-3.1c0.4-0.4,1-0.4,1.4,0S8.7,13.7,8.3,14.1z M20.4,17.2c-0.2,0.2-0.5,0.3-0.7,0.3s-0.5-0.1-0.7-0.3l-3.1-3.1c-0.4-0.4-0.4-1,0-1.4s1-0.4,1.4,0l3.1,3.1C20.8,16.2,20.8,16.8,20.4,17.2z M20.4,7.2l-7.6,7.6c-0.2,0.2-0.5,0.3-0.7,0.3s-0.5-0.1-0.7-0.3L3.8,7.2c-0.4-0.4-0.4-1,0-1.4s1-0.4,1.4,0l6.9,6.9L19,5.8c0.4-0.4,1-0.4,1.4,0S20.8,6.8,20.4,7.2z"/></svg>