Allow application/x-java-serialized-object media type without custom marshaller

The server registers a JavaSerializationTranscoder to make application/x-java-serialized-object available as a request/storage media type.

The core EncoderRegistryFactory registers instead a JavaSerializationEncoder, which can be used explicitly (cache.withEncoding(JavaSerializationEncoder.class)), but is not picked up automatically when the user configures storage media type application/x-java-serialized-object.