Keep only module-info.class in the root of runtime-fat-jar

[JaroslavTulach]

Pull Request Description

Additional fix to #8940. After this change there is only a single module info:

enso$ unzip runtime.jar module-info.class
enso$ javap module-info.class 
Compiled from "module-info.java"
open module org.enso.runtime {
  requires java.base;
  requires java.compiler;
  requires java.desktop;
  requires java.se;
  requires jdk.unsupported;
  requires org.graalvm.polyglot;
  requires org.graalvm.truffle;
  requires static org.slf4j;
  uses org.slf4j.spi.SLF4JServiceProvider;
  uses org.enso.interpreter.instrument.HandlerFactory;
  provides  com.oracle.truffle.api.provider.TruffleLanguageProvider with
    org.enso.interpreter.EnsoLanguageProvider,
    org.enso.interpreter.epb.EpbLanguageProvider;
  provides  com.oracle.truffle.api.instrumentation.provider.TruffleInstrumentProvider with
    org.enso.interpreter.instrument.ReplDebuggerInstrumentProvider,
    org.enso.interpreter.instrument.RuntimeServerInstrumentProvider,
    org.enso.interpreter.instrument.IdExecutionInstrumentProvider;
}

all other META-INF/versions/*/module-info.class files are dropped.

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• All code follows the
  Scala,
  style guides.
• All code has been tested:
  • Unit tests continue to pass

[Akirathan]

What a beautiful trick. No more custom merge strategies. So from now on, the runtime.jar should not be re-assembled if no source has changed.