ObjectAwareSerializationInterface is introduced for serializers that can serialize and deserialize PHP objects

To be able to differentiate between serializers like JSON or YAML which cannot serialize classed PHP objects, and serializers that can (eg. the PHP serializer),\Drupal\Component\Serialization\ObjectAwareSerializationInterface has been introduced. This interface can be used in type-hints or instanceof checks where object-serialization is required to make sure the right kind of serializer is passed.

Other change notices for same issue

• The database cache backend supports specifying a serializer
• ObjectAwareSerializationInterface is introduced for serializers that can serialize and deserialize PHP objects