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/routing/Loader/Configurator/Traits/PrefixTrait.php

@@ -0,0 +1,62 @@
+<?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\Component\Routing\Loader\Configurator\Traits;
+
+use Symfony\Component\Routing\Route;
+use Symfony\Component\Routing\RouteCollection;
+
+/**
+ * @internal
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+trait PrefixTrait
+{
+    final protected function addPrefix(RouteCollection $routes, $prefix, bool $trailingSlashOnRoot)
+    {
+        if (\is_array($prefix)) {
+            foreach ($prefix as $locale => $localePrefix) {
+                $prefix[$locale] = trim(trim($localePrefix), '/');
+            }
+            foreach ($routes->all() as $name => $route) {
+                if (null === $locale = $route->getDefault('_locale')) {
+                    $routes->remove($name);
+                    foreach ($prefix as $locale => $localePrefix) {
+                        $localizedRoute = clone $route;
+                        $localizedRoute->setDefault('_locale', $locale);
+                        $localizedRoute->setRequirement('_locale', preg_quote($locale));
+                        $localizedRoute->setDefault('_canonical_route', $name);
+                        $localizedRoute->setPath($localePrefix.(!$trailingSlashOnRoot && '/' === $route->getPath() ? '' : $route->getPath()));
+                        $routes->add($name.'.'.$locale, $localizedRoute);
+                    }
+                } elseif (!isset($prefix[$locale])) {
+                    throw new \InvalidArgumentException(sprintf('Route "%s" with locale "%s" is missing a corresponding prefix in its parent collection.', $name, $locale));
+                } else {
+                    $route->setPath($prefix[$locale].(!$trailingSlashOnRoot && '/' === $route->getPath() ? '' : $route->getPath()));
+                    $routes->add($name, $route);
+                }
+            }
+
+            return;
+        }
+
+        $routes->addPrefix($prefix);
+        if (!$trailingSlashOnRoot) {
+            $rootPath = (new Route(trim(trim($prefix), '/').'/'))->getPath();
+            foreach ($routes->all() as $route) {
+                if ($route->getPath() === $rootPath) {
+                    $route->setPath(rtrim($rootPath, '/'));
+                }
+            }
+        }
+    }
+}