Make transformers testing of subsystems use the legacy maven dependencies recursively rather than running the old subsystem on the new controller

To do something like what we do in core-model-test, where instead of just getting the legacy subsystem, we make the scoped classloader used for the legacy controller bring in the full set of dependencies for the subsystem, including its real controller. That will definitely get rid of these issues, and all the deprecated methods left around, but will need all the classloader trickery/proxies etc. done to load up the proxy controller and to be able to read/write to it. I think I have pretty much all the code for that, but will need to double-check if you like the idea. It will mean a big reorg of code and will take at least a few days. It also means that the tests will need to download a lot more from maven, I'm not sure if lightning has some cached private repo or not. We could probably only recursively bring in the org.jboss.as dependencies recursively to make it a bit more efficient, i.e. loading JPA for 7.1.2 should not need all the hibernate jars for that version since we are only testing the model part.