Add support for Supermin as an alternative to prebuilt images

[Conan-Kudo]

I was reminded today in a meeting about Supermin (made by @rwmjones). This would be a good way to support running kiwi in a VM when no existing box images are available, as it can produce the runtime image from repository inputs used in the image definition and thus have a perfectly matching image build host environment.

This could also make it interesting to integrate this functionality into the core of kiwi itself.