[Codegenerator] Version Support for Codegen Plugins

[juergen-albert]

In its current form, I can define a version in my -generate instruction. As far as I understand the code, this is only taken into account for generators, where a Main method is called.

https://github.com/bndtools/bnd/blob/5853f25a4146e8cc3331e6f4d7d79391021c3543/biz.aQute.bndlib/src/aQute/bnd/build/ProjectGenerate.java#L200-L211

For generator plugins, it seems to use the first or last version that is found. In our EMF Codegenerator workspace we want to use baselining. The baseline repo naturally contains the previous version of the codegenerator developed in this workspace. When I set the baseline repo, it always uses the old generator and the tests for the new features fail subsequently.

Thus it would be great to have a possibility to define a version(range) requirement for all types of generators. From my perspective it would be sufficient to use the bundle version. More fine grained on the plugin level would also be fine.