Integrate KST translator into the compiler
Currently translating KST specs is done with the [translator](https://github.com/kaitai-io/kaitai_struct_tests/tree/e443bd3e02e3159ab54ea5ba5a2245e1bc2ac698/translator) found in the tests repo. It relies on having built the compiler locally and is invoked with `sbt run ...`.

If it was part of the compiler it would be available to anyone that has the compiler installed and could be invoked with something like `ksc --kst ...`. It would also drop the dependency on Scala which makes Docker multi-stage builds leaner (mentioned in #714) and as a bonus it would be available from JS, too.