This PR introduces the follow changes to improve the build time to provide earlier feedbacks to contributors:

• Move definition of the docker build steps from Makefile to a docker-bake.hcl file

  • Benefit from using BuildX, but requires Docker 19.03+
  • Provide a foundation to define multiple images to prepare for Provide a multi-arch Docker Image #51, Rename image in Docker Hub to asciidoctor/asciidoctor #79, Docker Image with themes and labs plugin #85

• Use Github Container Registry to store the build cache

  • Builds are faster (reusing cache, in particular for the haskell intermediate image from Utilize multi-stage build to improve the image size #184 and chore: Faster builds #197)
  • A new make docker-cache target is introduced in the Makefile.
  • Cache is only pushed to the registry for branche workflows: pull request workflows does not have access to the credentials.
  • Cache is always used through buildkit as inline cache

• Update Makefile to support multiple images (to prepare Provide a multi-arch Docker Image #51, Rename image in Docker Hub to asciidoctor/asciidoctor #79, Docker Image with themes and labs plugin #85)

Expected build time improvement:

• When the cache is invalidated, no improvement (obviously)
• When cache is used, 2-3 min (depending on your network) instead of 13 min