Provide module descriptor

As this library has only 1 dependency (jakarta.el-api) which has a module descriptor, there's no blocking issue to add it here.

It could be done by hand, but as I see osgi support, it makes sense to generate it, so both are in sync.

Not sure if the felix plugin supports it, but https://github.com/bndtools/bnd/blob/master/maven-plugins/bnd-maven-plugin/README.md#bnd-process-goal does. https://bnd.bndtools.org/chapters/825-instructions-ref.html (`-jpms-module-info`)

module descriptors are required when creating applications using jlink.