No longer name the packageSetChains after the package set, but
keep them named after the pipelines. This should be a
non-functional change as dnf-json does not care about what the
chains are called, only that the names are unique.
Add a container image type that is based on the existing fedora
container image. There is a delta in terms of the configuration
because osbuild does not yet provide all the neccessary means,
but the package set is already very close.