Stunner: Provide missing components to client-side (un)marshalling

Some components that were injected in the backend are not available (yet?) in the front-end. In fact, these lines compile, but many required components are null:

https://github.com/evacchi/kie-wb-common/blob/b93a9d982f34f02764b0a8c42ba76fd6d17855c5/kie-wb-common-stunner/kie-wb-common-stunner-showcase/kie-wb-common-stunner-showcase-standalone/src/main/java/org/kie/workbench/common/stunner/standalone/client/services/BPMNStandaloneClientDiagramServiceImpl.java#L109-L163

At least FactoryManager should be provided; definitionManager, RuleManager, GraphCommandFactory, GraphCommandManager may be substituted by alternative implementations, if necessary. These are only required by the GraphBuilder object, which issues commands to the canvas: this is only invoked at the very end of the unmarshalling process.