Split up JavaModule

[lefou]

JavaModule and it's inheriting traits (ScalaModule, ScalaNativeModule, ...) combine various aspects which could also be used separately. We already extracted CoursierModule. Other aspects might be also worth to extract.

• Compiling things
• Running things
• Packaging and repackaging things

Once we split up functionality into more specific traits, we can refine existing traits like TestModule, which no longer would depend on the idea of compiling, but only on running things. That would it allow to defined additional test modules suppose to run different test frameworks on the same compiled classes. This was asked in chats multiple times.

• See Restructure TestModule, add RunModule  #3064

It would also allow to easily add some sub-module to configure additional (preconfigured) run targets. A topic often asked in the chats.

Of course, this is most likely an binary incompatible change, since mix-in new traits in JavaModule and calling the super-def isn't a binary-compatible change.