Abstract Proxy to allow plugging of a Scala Kompics version

[Bathtor]

We need to do the same in the testing framework that I did in Kompics Java, back, when I first wrote Kompics Scala, that is separate out what the (test-)runtime requires to be able to interact with the CUT into an interface or abstract class (or multiple) and then select whether to use a Java or Scala implementation of this abstraction based on the the actual runtime type of the CUT.

Otherwise we won't ever be able to have a working Scala DSL, or even just use the testing framework with Kompics Scala components.