[Experimental] - Integration tests refactor

I find that my test-specific setup is minimal, while my integration-test specific setup is much more (downloading runtimes, setting properties, etc).  If I had the two integration test plugins inside a tests folder rather than itests, i couldnt put such config in tests/pom.xml bc its not common to all tests, and i'd need to duplicate it instead in the two integration test plugins' pom.xml files.