Add Github Actions config for multi-arch Docker Image build and push to repository

[francisli]

Note, we can perhaps accelerate multi-arch build times by using separate native x86/ARM runners and combining the images after:

https://andrewlock.net/combining-multiple-docker-images-into-a-multi-arch-image/

https://docs.docker.com/build/building/multi-platform/#multiple-native-nodes

https://docs.docker.com/build/ci/github-actions/multi-platform/#distribute-build-across-multiple-runners