- Add a multi-arch image with linux/amd64 and linux/arm64 (limit to just
what we are running in CI)
- Bump versions to 2.0 as 1.0 is the single-arch image
- Use `docker buildx` instead of just docker, so we don't need to build
manifests by hand
- busybox now does not have `nogroup`, since the test needs it, switch
over from busybox to ubuntu for just the volume-ownership image
Signed-off-by: Davanum Srinivas <davanum@gmail.com>
