Make it possible to build a combined engine&cli image

[vvoland]

To move away from the legacy docker-ce-packaging before we decouple engine releases from the cli releases we should have a workflow that produces a single image with Engine & CLI.

We should have 3 archives with static binaries:

• docker-major.minor.patch.tgz (for compatibility with the current https://download.docker.com/linux/static/stable/x86_64/)
• docker-engine-major-minor.patch.tgz (only engine)
• docker-cli-major-minor.patch.tgz (only engine)

This will allow to drop https://github.com/docker/release-packaging in favor of docker/packaging.

[crazy-max]

• docker-major.minor.patch.tgz (for compatibility with the current https://download.docker.com/linux/static/stable/x86_64/)

Hum that will change our packaging quite a bit 🤔 Not sure how we can achieve this without merging https://github.com/docker/packaging/tree/main/pkg/docker-cli and https://github.com/docker/packaging/tree/main/pkg/docker-engine packages together but that would break non-static packages.

Maybe it could be done on release-repo directly by merging both cli and engine static tarballs?

Also should we publish static for cli plugins?

[vvoland]

I think it would be fine to have a separate package that has both cli and engine for now.

Also should we publish static for cli plugins?

We haven't been doing it now.. Maybe we should? Although I think we'd need to figure out the macOS/Windows signing first so these are actually useable.