Publish Docker image for linux/arm64 platform

[keynmol]

Easiest way to start is to make the Docker build multi-staged, see https://github.com/sourcegraph/scip-go/pull/32/files for example.

After that, the story around cross-publishing is well documented.

I believe this entire block is copypastable with minimal adjustments: https://github.com/indoorvivants/sn-vcpkg/blob/main/.github/workflows/ci.yml#L163-L256