Use DMNContextFPAImpl for DMNRuntime evaluation

DROOLS-5517 is implemented like:
1) DMNRuntimeImpl creates a DMNContextImpl from DMNContextFPAImpl
2) DMNRuntimeImpl evaluation goes through with DMNContextImpl
3) Before responding to the client, create DMNContextFPAImpl with OutputSet and return

This JIRA aims to use DMNContextFPAImpl for DMNRuntimeImpl evaluation instead of converting to DMNContextImpl.

A partial implementation:
https://github.com/tkobayas/drools/tree/DROOLS-5517-use-FPA-for-evaluation