[PHP-Symfony] Encurage Symfony 5 bundle directory structure best practices (#13014)

* use .yaml instead of .yml

This is recommended by Symfony standards

* save Bundle files also to src path

* add test for generate ping

* add package imports

* fix expected file names

* why is Api/ApiServer.php missing

* output filenames

* use getAbsolutePath for debug purpose

* do not use punctuation as current directory

* refactor: remove todos

* use also .yaml in test to fix it

* add test for setting a different source directory

* use correct const for setting source dir property in tests

* import the AbstractPhpCodegen in test class

* put also Resources to source path

* save docs not to Resources

* update samples and improve src path in autoload.php and composer.json

* update moved samples

samples/server/petstore/php-symfony/SymfonyBundle-php/Tests/AppKernel.php

@@ -24,6 +24,6 @@ class AppKernel extends Kernel
      */
     public function registerContainerConfiguration(LoaderInterface $loader)
     {
-        $loader->load(__DIR__.'/test_config.yml');
+        $loader->load(__DIR__.'/test_config.yaml');
     }
 }

samples/server/petstore/php-symfony/SymfonyBundle-php/Tests/test_config.yaml

@@ -1,8 +1,8 @@
 imports:
-    - { resource: "../Resources/config/services.yml" }
+    - { resource: "../Resources/config/services.yaml" }
 
 framework:
     secret: "testsecret"
     test:   ~
     router:
-        resource: "%kernel.project_dir%/Resources/config/routing.yml"
+        resource: "%kernel.project_dir%/Resources/config/routing.yaml"