We used to have a minimal image back in the Fedora 32 days,
but it got lost along the way. Reintroduce it.
I didn't try too hard to make it as small as possible, but
simply by taking care of the low-hanging fruits I was able to
go from the ~7.5GB of the developer image to ~2.2GB, which is
already a significant improvement.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>