Make DefinitionService / BPMN2 info functionality to other modules without bringing all of the jbpm-kie-services dep tree along

For Change Impact, the Designer BPMN2FileIndexer needs to be able to parse and extract BPMN2 metadata – and for that, we need the functionality that's implemented in the (old) BPMN2DataServiceImpl.

This issue is to make that functionality somehow available without having to bring all of the other jbpm-kie-services code and dependency tree along.