Dockerfile/Containerfile for Arti

It would be great to have a Dockerfile (our Containerfile) for Arti.

Things to consider:

Environment variables to tune Arti's build options.
Defaults that work for most cases.
Tags for different OSes and architectures? Which ones makes sense?
Onion Services support (if not on the default image, at least in a tag/variant).
CI for building images and publishing in a Container Registry.