feature #21854 [Router] Follow symlinks and skip dots in the annotation directory loader (jakzal)

This PR was merged into the 3.3-dev branch.

Discussion
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[Router] Follow symlinks and skip dots in the annotation directory loader

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Following #21833, this change will make the `AnnotationDirectoryLoader` consistent with other loaders.

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Commits
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344114024b [Router] Follow symlinks and skip dots in the annotation directory loader

src/Symfony/Component/Routing/Loader/AnnotationDirectoryLoader.php

@@ -40,7 +40,7 @@ class AnnotationDirectoryLoader extends AnnotationFileLoader
         $collection->addResource(new DirectoryResource($dir, '/\.php$/'));
         $files = iterator_to_array(new \RecursiveIteratorIterator(
             new \RecursiveCallbackFilterIterator(
-                new \RecursiveDirectoryIterator($dir),
+                new \RecursiveDirectoryIterator($dir, \FilesystemIterator::SKIP_DOTS | \FilesystemIterator::FOLLOW_SYMLINKS),
                 function (\SplFileInfo $current) {
                     return '.' !== substr($current->getBasename(), 0, 1);
                 }