Add integration and unit tests for PersonJsonNormalizer to verify normalization behavior

- Introduce `PersonJsonNormalizerIntegrationTest` to test database-driven normalization scenarios.
- Expand `PersonJsonNormalizerTest` with cases covering minimal group normalization and extended keys.
- Refactor test setup to use mock objects and improve coverage of normalization logic.

src/Bundle/ChillPersonBundle/Serializer/Normalizer/PersonJsonNormalizer.php

@@ -78,11 +78,6 @@ class PersonJsonNormalizer implements NormalizerAwareInterface, NormalizerInterf
             null];
     }
 
-    public function supportsDenormalization($data, $type, $format = null)
-    {
-        return Person::class === $type && 'person' === ($data['type'] ?? null);
-    }
-
     public function supportsNormalization($data, $format = null): bool
     {
         return $data instanceof Person && 'json' === $format;