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/css-selector/XPath/Extension/ExtensionInterface.php

@@ -30,40 +30,38 @@ interface ExtensionInterface
      *
      * @return callable[]
      */
-    public function getNodeTranslators();
+    public function getNodeTranslators(): array;
 
     /**
      * Returns combination translators.
      *
      * @return callable[]
      */
-    public function getCombinationTranslators();
+    public function getCombinationTranslators(): array;
 
     /**
      * Returns function translators.
      *
      * @return callable[]
      */
-    public function getFunctionTranslators();
+    public function getFunctionTranslators(): array;
 
     /**
      * Returns pseudo-class translators.
      *
      * @return callable[]
      */
-    public function getPseudoClassTranslators();
+    public function getPseudoClassTranslators(): array;
 
     /**
      * Returns attribute operation translators.
      *
      * @return callable[]
      */
-    public function getAttributeMatchingTranslators();
+    public function getAttributeMatchingTranslators(): array;
 
     /**
      * Returns extension name.
-     *
-     * @return string
      */
-    public function getName();
+    public function getName(): string;
 }