Add module-info.java

[Sineaggi]

Adds a new java compile task (depends on jvm dependencies and kotlin class files) to compile a module-info.java file, and puts it into the jvm jar.

I've never done this for a kotlin-multiplatform project, so I'm sure there are improvements. I looked into using multi-platforms 'withJvm' feature, but that dropped the files that were compiled with java 8 directly into the resulting jar. At least with this custom sourceset approach, we can compile the file with java 9 and put the module-info.class file where we want (META-INF/versions/9).