Mark the DI extension and the Configuration classes as internal

Those classes are meant to be used only as implementation of the bundle
semantic configuration, not directly.

Author: stof

src/DependencyInjection/Configuration.php

@@ -6,6 +6,9 @@
 use Symfony\Component\Config\Definition\Builder\TreeBuilder;
 use Symfony\Component\Config\Definition\ConfigurationInterface;
 
+/**
+ * @internal
+ */
 class Configuration implements ConfigurationInterface
 {
     public function getConfigTreeBuilder(): TreeBuilder

src/DependencyInjection/StofDoctrineExtensionsExtension.php

@@ -11,6 +11,9 @@
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 
+/**
+ * @internal
+ */
 class StofDoctrineExtensionsExtension extends Extension
 {
     private const LISTENER_EVENTS = array(