Provide builds for Apple M1 processors

[pverscha]

On modern Apple computers with an ARM-based CPU, Docker images that are originally built for computers with an x86-based CPU need to be emulated using qemu. This is all done automatically by Docker, but could lead to a significant performance slowdown during the construction of a database.

In order to resolve this issue, we should also provide dedicated ARM-based Docker images and push these to Docker Hub. See this guide for more information about how to do this: https://docs.docker.com/desktop/multi-arch/#build-multi-arch-images-with-buildx

[pverscha]

An ARM64-version (with native support for Apple M1 CPU's) is now available for the Unipept Database image. A native version of the Unipept Web image is not yet available, this will be made available once the Unipept API has been migrated to it's own repository and no longer depends on TheRubyRacer.