This adds the OpenAPI spec for the new composer-koji API. This API is meant
to expose expose just the functionality needed to generate images and push
them to koji.
Each compose may consist of several images, each image may have a
different architecture and image type, and the set of repositories with
their contents may be distinct. However, a compose is restricted to one
distro and one koji transaction.
Signed-off-by: Tom Gundersen <teg@jklm.no>
