Custom Denormalizer are not used anymore when deserializing relation inside Input

[VincentLanglet]

API Platform version(s) affected: 4.2.17 or 4.2.18

Related to the fixes (cc @soyuka)
#7779
#7787

With something like

#[ApiResource]
class Locale { private string $id; }

class MyInput { private Locale $locale }

When calling the endpoint with the data ['locale' => 'en'] it's expected to not denormalize the Locale since it's not an IRI.
But I wrote my custom LocaleDenormalizer which basically does $this->entityManager->getRepository(Locale::class)->find($data); and it worked find before the upgrade.

Looking at how it worked,

• The serializer used the ItemNormalizer
• The class is changed, and now it used the ObjectNormalizer from Symfony (cf analyze from Input DTOs are not being passed through the name converter #7705 (comment)) for $locale field.

Now, it use the ItemNormalizer and keep using it for the locale field. But then since this field is a string, it tries to resolve the IRI without calling the denormalizer on it. And I get a Invalid IRI error.

I think rather than always using the iriConverter, the ItemNormalizer should call serializer::normalize on the string value:

• If a denormalizer has a higher priority it will be used
• If not, it will fallback on the ItemNormalizer again which already handle string value with the IriConverter the right way.

A fix like #7830