PureharmTestRuntimeLazyConversions

Basically the problem is as such:

1. ideally, you probably want only one PureharmTestRuntime instantiated in your entire test run to not waste resources and startup time...
2. and you want easy usage...

To achieve 2) we could make it a val runtime, and do import runtime._ in the tests, and all would be good!

But then 1) is impossible...

By doing this trick the runtime is instantiated as late as possible, and you get all the necessary imports in your tests usage as well!