documentation #4958 3.x doc fixes (fabpot)

This PR was squashed before being merged into the 3.x branch.

Discussion
----------

3.x doc fixes

Commits
-------

1478f9efcd Fix the class name and a missing parenthesis in the runtime loader example
e883536e64 Replace the deprecated twig_test_even function in the custom test example
db3aeb7379 Use the current variable node class in the node tree example

doc/advanced.rst

@@ -848,7 +848,7 @@ The ``getTests()`` method lets you add new test functions::
         public function getTests()
         {
             return [
-                new \Twig\TwigTest('even', 'twig_test_even'),
+                new \Twig\TwigTest('even', fn (int $value): bool => 0 === $value % 2),
             ];
         }
 
@@ -919,8 +919,8 @@ a runtime extension using one of the runtime loaders::
     }
 
     $twig = new \Twig\Environment($loader);
-    $twig->addExtension(new \Twig\Extension\AttributeExtension(ProjectExtension::class);
-    $twig->addRuntimeLoader(new \Twig\RuntimeLoader\FactoryLoader([
+    $twig->addExtension(new \Twig\Extension\AttributeExtension(ProjectExtension::class));
+    $twig->addRuntimeLoader(new \Twig\RuntimeLoader\FactoryRuntimeLoader([
         ProjectExtension::class => function () use ($lipsumProvider) {
             return new ProjectExtension($lipsumProvider);
         },

doc/internals.rst

@@ -95,7 +95,7 @@ Here is the output for the ``Hello {{ name }}`` template:
     \Twig\Node\ModuleNode(
       \Twig\Node\TextNode(Hello )
       \Twig\Node\PrintNode(
-        \Twig\Node\Expression\NameExpression(name)
+        \Twig\Node\Expression\Variable\ContextVariable(name)
       )
     )