Stunner - remove serialization/deserializatin for Data Assignmetns Variables

Right now Data I/O Assignments Serialization/Deserialization variables during transferring from marshaller to UI and from UI to marshallers. It was done previously for seamless migration from old marshallers to new one.

Now, migration is happend but we still have this code which already causes some regression issues like RHPAM-2990, RHPAM-3015 and similar.

To prevent this kind of issues in the future we can remove Serialization/Deserialization and transfer objects directly from Marshallers to Ui and backward. It will simplify overall design and code base of both UI and Marshallers and will let to catch issues during compile time.