Publish RC container images (#7556)

* WIP

* Add missing checkout

* Add debuggin

* Fix VAR name

* Bug fix

* Rework jobs

* Revert "Rework jobs"

This reverts commit 2bfa79fd3ae633c17403b838f9a5025f0f7fc3f3.

* Add cache

* Add temp default for testing

* Add missing checkout

* Fix patch

* Comment out the GPG check for now

* Rename polkadot_injected_release into a more appropriate polkadot_injected_debian

* Refactoring / renaming

* Introduce a generic image for binary injection

* Flag files to be deleted and changes to be done

* WIP

* Fix multi binaries images

* Add test build scripts

* Remove old file, add polkadot build-injected script

* Fix doc

* Fix tagging

* Add build of the injected container

* Fix for docker

* Remove the need for TTY

* Handling container publishing

* Fix owner and registry

* Fix vars

* Fix repo

* Fix var naming

* Fix case when there is no tag

* Fix case with no tag

* Handle error

* Fix spacings

* Fix tags

* Remove unnecessary grep that may fail

* Add final check

* Clean up and introduce GPG check

* Add doc

* Add doc

* Update doc/docker.md

Co-authored-by: Mira Ressel <[email protected]>

* type

Co-authored-by: Mira Ressel <[email protected]>

* Fix used VAR

* Improve doc

* ci: Update .build-push-image jobs to use the new build-injected.sh

* ci: fix path to build-injected.sh script

* Rename the release artifacts folder to prevent confusion due to a similar folder in the gitlab CI

* ci: check out polkadot repo in .build-push-image

This seems far cleaner than copying the entire scripts/ folder into our
job artifacts.

* feat(build-injected.sh): make PROJECT_ROOT configurable

This lets us avoid a dependency on git in our CI image.

* ci: build injected images with buildah

* ci: pass full image names to zombienet

* Add missing ignore

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Co-authored-by: Mira Ressel <[email protected]>