set authzforce-ce-core-pdp-api version to 9.1.0

order to make test utilities a reusable maven artifact, that can be
reused to test extensions and also in server/webapp tests:
	- pdp-engine
	- pdp-testutils
	

	- Change of type in AttributeGUID constructor's issuer parameter from
String to Optional <String>
	- Change of type in StatusHelper constructor's message and detail
parameters, from String to Optional<String>
	- Change of type returned by Datatype#getTypeParameter(): Datatype<?>
-> Optional<Datatype<?>>

numeric operators add and multiply)

multiply functions) - merge/replace all constant args into/with one

and RootPolicyEvaluators

for it)

- Renamed LocalPdpBasedAuthzInterceptor* test classes to
EmbeddedPdpBasedAuthzInterceptor*
- Added null check in MapFunctionFactory for checking if sub-function
return type parameter is null (wrong)

org.ow2.authzforce.core.pdp.impl.test
- Refactored unit test and sample code for CXF authorizing interceptor
(PEP)