OCI: fix rockcraft build and multi-arch amd64+arm64

[arelange]

Adding support for multi-arch container deployment in CI
Currently only with the following architectures:

• amd64
• arm64

Fixing by the way a failure that seemed to have appeared with latest version of rockcraft

[tillkamppeter]

Hi, thanks for your PR.

One question: As you have merged your 2 commits into one it is not visible any more how you have fixed the Rockcraft build failure. Could you tell here what was wrong and how did you fix it?

Also could you tell why this PR is still a draft? What do you plan to still do with it before it can get merged?

[tillkamppeter]

Also, are you pushing the container images to DockerHub? To which owner there? As these are official packages from OpenPrinting they should be, if they are uploaded to DockerHub, be owned by OpenPrinting there.

[tillkamppeter]

Your builds for ARM have failed by the way ...

[arelange]

well well...
when I opened the pull request 14 months ago, the build and github pipeline were failing due to an automated breaking update of rockcraft. so I fixed that but my main intent was to enable multi-arch AMD64+ARM64 containers, and everything was working fine.

Few months later, the build and pipelines working again, I wanted to give it a try to rebase the multi-arch part on top of the head (actually more for me than for anyone else, after that time I did not expect any interest anymore in that PR)
quickly noticing the arm64 pipeline was failing, I switched this PR to draft as it would require a bit more work than I can handle before going to work.

Finally as for pushing to dockerhub, I have no intent doing so. But current github actions still has commented code to do so, probably used in the past and kept to be reactivated one day. I tried to keep that spirit and update the commented code to support also multi-arch container release on dockerhub.
I am open to clean those if needed.

[tillkamppeter]

Thanks for the clarifications.

Sorry for not having reacted in the first place. I must have overlooked it.

Could you make a separate PR to just fix the original bug and then take your time to complete the addition of multi-arch CI?

This way once, the bug will get fixed more quickly, and second, one can tell the fix and the CI addition.