New transformer infrastructure

[gtrepta]

The scala transformers over the kore data structures have multiple pain points and need to be redesigned.

Something in Java, and with an interface more akin to the LLVM passes would be more flexible.

[gtrepta]

I've landed on a design I'm happy with for an abstract base class of a pipeline stage: 3f26e40

This should be flexible enough to implement the transformations we want to make in the compiler pipeline. It isn't a total 1-to-1 mapping of the scala transformers, notably handling exceptions on sentences doesn't exist yet, but the transformers in the kore pipeline should be implementable without nearly as many lambda expressions.

[Baltoli]

Discussed with @gtrepta yesterday; we're holding off on the full generality of being able to specify pipeline orderings / dependencies etc. as it's not clear we need that much abstraction yet. What will be useful in the shorter term is the Java -> Scala translation; we should adopt the parts of Guy's design that are relevant there when we come to port it away from Scala.

@gtrepta I've assigned you here; if there's a way to get the Java port + cleanup merged without the dependency ordering part of the change then that would be great, if it's not trivial then we can leave it for now and revisit when we come to remove the last of the Scala code.