Make jmods available from the jdk BUILD file

[srdo-humio]

The PR at https://github.com/bazelbuild/rules_java/pull/135 looks dormant, this makes the change requested at https://github.com/bazelbuild/rules_java/pull/135#issuecomment-1797985514

I don't need the entire change here, having the jmods as a filegroup is sufficient for using jlink, but @cushon suggested adding the files as sources to the java_runtime as well, if I understood him correctly, so I did that too. If that's not necessary, let me know and I'll remove that part.