Runners for aarch64/armv7

[dragonchaser]

We need to add a couple of custom runners for the arches mentioned, for aarch64 we could go for aws graviton instances.

• Create a generic way to start ARM (v7/hf and aarch64) runners with a Docker image to start the runner in the same environment, and have a oneliner documented to start it and attach it to the cOS repository
• Finding out a location where to run a permanent runner (AWS, internal ... ?, for now it is running on ec2 and attached to the project)
• Setup the github runner and attach it to repository to run arm workflow (default label: $ARCH, $OS, self-hosted)

[mudler]

we can also use aws aarch64 for arm7 as well

[mudler]

We need to talk to @pgonin first, I'm not sure if we can automatically scale graviton instances, so maybe those should be up and running always in the worse case.

We might get some internal runners, but blocking this since we need some feedback first.

[mudler]

Re: the images, we could use qemu-binfmt in GHA to build and push the docker images for arm platform

[mudler]

@dragonchaser are you already looking into this one right?

[dragonchaser]

Doing some experiments on docker buildx on the side....

[dragonchaser]

I have created a docker image wich can be spawned on arm32v7, aarch64 and amd64.
https://github.com/dragonchaser/dockerhub-autobuild/tree/master/ghrunner
I have tried it on aarch64 with ec2 and also with a docker-swarm running on some raspberry pis.

[dragonchaser]

PR: #605