Docker: Multi-Arch Support

[mopfel-winrux]

The official docker image should support both amd64 and arm64 virtualization.

ARM is slowly becoming the cheapest and most energy efficient way to run servers. Having an official docker image will make running Vere on devices like Raspberry Pi's (and clones) much easier.

Currently the docker image is built using Bazel's docker build functionality. This however only seems to allow one arch type at a time.

Native Planet is currently doing automated multiarch builds using docker's buildx command. This is automated using our jenkins build server. This is all to say that we can build a docker image without using Bazel if necessary. The repo can be found https://github.com/Native-Planet/urbit-docker.

[yapishu]

I believe arm builds have to wait for this to get merged upstream: bazelbuild/rules_docker#2087

[belisarius222]

bazelbuild/rules_docker#2087 (comment)

Well, that doesn't look good.