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/service-contracts/ResetInterface.php

@@ -0,0 +1,30 @@
+<?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\Contracts\Service;
+
+/**
+ * Provides a way to reset an object to its initial state.
+ *
+ * When calling the "reset()" method on an object, it should be put back to its
+ * initial state. This usually means clearing any internal buffers and forwarding
+ * the call to internal dependencies. All properties of the object should be put
+ * back to the same state it had when it was first ready to use.
+ *
+ * This method could be called, for example, to recycle objects that are used as
+ * services, so that they can be used to handle several requests in the same
+ * process loop (note that we advise making your services stateless instead of
+ * implementing this interface when possible.)
+ */
+interface ResetInterface
+{
+    public function reset();
+}