[Symfony73] Keep AbstractExtension when Twig extension overrides a built-in function/filter

[TomasVotruba]

When a Twig extension overrides a built-in Twig function/filter (e.g. include, date, escape), the override only works while the class stays a classic extends AbstractExtension. The #[AsTwigFunction] / #[AsTwigFilter] attribute-based registration cannot override core Twig callables the same way.

GetFunctionsToAsTwigFunctionAttributeRector (and its filter sibling, via the shared transformer) now skips such built-in-named items: they stay in the array and the class keeps extends AbstractExtension. Other, non-built-in items in the same class are still converted.

Skip a pure built-in override

final class OverrideIncludeExtension extends AbstractExtension
{
    public function getFunctions(): array
    {
        return [
            // Override the built-in include function with higher priority
            new TwigFunction('include', $this->includeWithEvent(...), [
                'needs_environment' => true,
                'needs_context'     => true,
                'is_safe'           => ['html'],
            ]),
        ];
    }
    // ...
}

No change — the class keeps AbstractExtension because include is a built-in.

Convert custom, keep built-in

 final class KeepBuiltinConvertCustom extends AbstractExtension
 {
     public function getFunctions(): array
     {
         return [
             new TwigFunction('include', $this->includeWithEvent(...), ['needs_environment' => true]),
-            new TwigFunction('custom_function', [$this, 'customFunction']),
         ];
     }

     public function includeWithEvent(Environment $env, $template)
     {
         return $template;
     }

+    #[\Twig\Attribute\AsTwigFunction(name: 'custom_function')]
     public function customFunction($value)
     {
         return $value;
     }
 }

The custom function becomes an attribute; the include override stays registered the classic way, so AbstractExtension is preserved.