XACML Decision support for Multiple Requests

As an ONAP Decision API callee, I would like to combine Decision Requests into one single request so that I can avoid making too many REST calls to the Decision API. This is most useful in the Guard Application, to test multiple "targets" at one time.

Note that the Monitoring/Naming applications already supports this via using a "Combined Results" algorithm that combines all the permits. But that solution is not what is desired in that the Guard wants to understand which targets are Denied as well as Permitted.

Optimization/Match are specific to the OOF requirements and thus should remain as is.

Native supports multi-requests OOB since it's simply a pass through of the standard XACML Decisions.