Draft: Resolve #3495440 "Declaration of drupalserializationnormalizeranynormalizernormalize"

Closes #3495440

• Adding "supportsNormalization" method to avoid exceptions as:

Symfony\Component\Serializer\Exception\NotNormalizableValueException: Could not normalize object of type "Drupal\Core\Menu\MenuLinkTreeElement", no supporting normalizer found. in Symfony\Component\Serializer\Serializer->normalize() (line 181 of /var/www/html/vendor/symfony/serializer/Serializer.php).

• updating the signature

src/Normalizer/MenuLinkNormalizer.php

@@ -20,7 +20,14 @@ class MenuLinkNormalizer extends NormalizerBase {
   /**
    * {@inheritdoc}
    */
-  public function normalize($object, $format = NULL, array $context = []) {
+  public function supportsNormalization($data, ?string $format = null, array $context = []): bool {
+    return $data instanceof MenuLinkInterface;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function normalize($object, ?string $format = NULL, array $context = []): array {
     /** @var \Drupal\Core\Menu\MenuLinkInterface $object */
     return [
       'id' => $object->getPluginId(),