Recover ability to register AST transformer factories in Symfony Bundle

docs/_nav.md

@@ -13,6 +13,7 @@
     - [Transformer](mapping/transformer.md)
     - [Provider](mapping/provider.md)
     - [Mapping inheritance](mapping/inheritance.md)
+    - [AST transformer factory](mapping/ast_transformer_factory.md)
 - [Symfony Bundle](bundle/index.md)
     - [Installation](bundle/installation.md)
     - [Configuration](bundle/configuration.md)

docs/mapping/ast_transformer_factory.md

@@ -0,0 +1,26 @@
+# AST transformer factory
+
+> [!WARNING]
+> AST transformer factories are for very advanced usage and often not required, please use them with caution
+
+Sometimes we need to manage more complex objects that need specific behavior during mapping. For example the 
+`Money\Money` object [from the Money PHP library]((https://github.com/moneyphp/money)) has a lot of properties we 
+don't want to manage and can confuse the AutoMapper since it will try to map any properties.
+
+You could do it with a [custom transformer](./transformer.md) but it means you will have to declare each property that
+needs to use this custom transformer. That is why AST transformer factory is here, it will automatically generate code 
+to map your data thanks to AST.
+
+You can see [such a class in our test suite](https://github.com/jolicode/automapper/blob/main/tests/Fixtures/Transformer/MoneyTransformerFactory.php)
+as a working example. You will need to register the factory in the `AutoMapper` instance.
+
+```php
+use AutoMapper\AutoMapper;
+
+$autoMapper = AutoMapper::create(transformerFactories: [new MoneyTransformerFactory()]);
+```
+
+> [!NOTE]
+> When using the Symfony Bundle version of the AutoMapper, you just need to implements the `TransformerFactoryInterface`
+> interface and if you have autoconfiguration enabled, you do not need to register the factory manually as the tag will 
+> be automatically added.

src/Symfony/Bundle/DependencyInjection/AutoMapperExtension.php

@@ -19,6 +19,7 @@
 use AutoMapper\Symfony\Bundle\ReflectionClassRecursiveIterator;
 use AutoMapper\Transformer\PropertyTransformer\PropertyTransformerInterface;
 use AutoMapper\Transformer\SymfonyUidTransformerFactory;
+use AutoMapper\Transformer\TransformerFactoryInterface;
 use Symfony\Component\Config\Definition\ConfigurationInterface;
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -89,6 +90,8 @@ public function load(array $configs, ContainerBuilder $container): void
             $container->setParameter('automapper.cache_dir', $config['loader']['cache_dir']);
         }
 
+        $container->registerForAutoconfiguration(TransformerFactoryInterface::class)->addTag('automapper.transformer_factory');
+
         if (class_exists(AbstractUid::class)) {
             $container
                 ->getDefinition(SymfonyUidTransformerFactory::class)