[enhancement] Support Docker, BuildKit, img, Buildah, and Kaniko

[gaocegege]

Now we rely on s2i to build the image, then need to push it to a registry. As @inc0 suggested, we should investigate if knative build is better.

[gaocegege]

/priority p3

[gaocegege]

Ref https://github.com/kubeflow/kubeflow/issues/289

• https://github.com/genuinetools/img
• https://github.com/containerbuilding/cbi
• https://github.com/GoogleContainerTools/kaniko
  • kaniko does not support ARG and SHELL Dockerfile commands - we use these for building jupyter images

[gaocegege]

img is a promising tool since it does not require docker daemon, and support pushing

[gaocegege]

kaniko also works for us since it provides docker-push as a service.

It is only supports three contexts:

• GCS Bucket
• S3 Bucket
• Local

[gaocegege]

There is a benchmark for these tools: https://github.com/AkihiroSuda/buildbench

https://github.com/AkihiroSuda/buildbench/issues/5

[gaocegege]

I think there is no need to do it now. We should be k8s native and rely on configmaps or volumes