Add JPMS module-info.java

[nedtwigg]

I'm not sure that anyone will ever need this. But I mistakenly thought that we did to reproduce a user bug, so I started experimenting in the feat/module-info branch (see diff).

The hiccups I ran into were:

• the module-info.java has to be in a java folder, not a kotlin folder
• stuff that is in the java folder can't reference stuff in the kotlin folder
• we needed fake package-private NeededForModuleInfo.java files in the java folder to avoid compilation errors in the module-info.java

If you need selfie to support module-info.java, I'm happy to merge a PR that does it, and you can use this as a starting point.

• the hiccups above are fine with me. If you can fix the workarounds great, but I don't mind shipping them
• please merge in from main first, maybe the latest version of the Kotlin plugin will have made it easier by then
• I would like the metadata (naming and whatsuch) to be canonical, and I don't have enough experience with JPMS to know what it should be. Hopefully if you need JPMS, you've also got enough experience that you can set this metadata better than I did.