Support for JPMS, add module-info.java

Putting things into a context of a coded project, a real project, all sane developers want JPMS.

I just took a new look at the JAR downloaded from the Maven artifact named "fr.inria.gforge.spoon:spoon-core:11.3.1-beta-8" (just released two days ago). It continues to be without any valid module-info, that is, contain information from a valid `module-info.jar`.

Would it be possible to establish spoon-libraries as valid modules? With the purpose that they fit into normal contexts of usages, do not stick out, do not need post-processing, have their doing verified and upheld at runtime? Fit into normal, strict, more modern Java development?

Request: Please add valid module information to the spoon-modules!

Start by examining how the spoon-modules are built and how the Maven artifact fr.inria.gforge.spoon:spoon-core:11.3.1-beta-8 is published, then review the JPMS requirements for valid module information. Done means the spoon libraries publish valid module metadata without post-processing and work in strict modern Java projects.

Written by the indexing model from the issue text.