Giving the projects a Maven structure

[JaroslavTulach]

This pull request gives the existing sources a Maven structure in order to let the code be approachable by majority of Java IDEs. As a result it is possible to code, compile, run & debug the project using for example GraalVM's Ideal Graph Visualizer (part of GraalVM EE tools). Here are the steps:

Download IGV 20.0.1 and then:

$ unzip idealgraphvisualizer-20.0.1-all.zip 
$ chmod +x idealgraphvisualizer/java/maven/bin/mvn
$ ./idealgraphvisualizer/bin/idealgraphvisualizer --userdir ud --jdkhome /jdk-13

Then select File/Open Project... and locate the graal_service_issue project with this PR changes applied. In the open project dialog check Open Required Projects checkbox to open the main Maven project as well as its two subprojects.

Make sure Projects window is selected and right click org.grfstuff.pom project and invoke clean build.

Open (Ctrl+O) GrfStuffHotSpotBackendFactory and put a breakpoint (Ctrl+F8) on its line 11 which contains the debug System.out.println output.

Back into the Projects window. Right click org.grfstuff.violajones and select Debug. Your breakpoint is going to be hit properly.

Enjoy coding and especially debugging with GraalVM's Ideal Graph Visualizer.

[grfrost]

Thanks for this. I will try it. Usually I am not amaven fan, but if it will help I am in!