Move project away from Earthly

[claraberendsen]

Since we set up this project beginning of last year Earthly has become unmaintained (See https://earthly.dev/blog/shutting-down-earthfiles-cloud/).

Alternatives:

• Docker Bake
• Dagger
• Plain docker with some extra sparkles.

Earthly provided an ergonomic way of configuring these multiple parallel builds to test and debug.

[KmoM88]

I've created a repo with a comparison of the tools (only dagger and bake) migrating the first job of build and test deb packages to help evaluate the options. Hope it helps!
https://github.com/KmoM88/earthly-alternatives