Verify artifacts in bootc container images

[vraiti]

Runs a simple script inside each container using rpm to check that flightctl-agent has been installed.

[vraiti]

@oglok @astoycos finished rebasing the changes from #17. Could you take a look?

[oglok]

This PR needs a rebase as there are conflicting files.

[astoycos]

Workflow failed to run

https://github.com/flightctl/flightctl-demos/actions/runs/9648683438

[astoycos]

So login/ push will always fail on the PR flow, you can do something like https://github.com/bpfman/bpfman/blob/main/.github/workflows/image-build.yaml#L160 Where you can conditionally only run the registry login and push on scheduled (https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule) with if: ${{ github.event_name == 'schedule' }}

and then

      - name: Set push flag
        id: set-push
        run: |
          if [ ${{ github.event_name }} == 'push' ]; then
            echo "push_flag=true" >> "$GITHUB_OUTPUT"
          else
            echo "push_flag=false" >> "$GITHUB_OUTPUT"
          fi

      - name: Build and push
        id: build-push-image
        uses: docker/build-push-action@v5
        with:
          platforms: linux/amd64, linux/arm64
          # TBD: linux/ppc64le, linux/s390x
          push: ${{ fromJSON(steps.set-push.outputs.push_flag) }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          file: ${{ matrix.image.dockerfile }}
          build-args: ${{ matrix.image.build_args }}
          context: ${{ matrix.image.context }}

Therefore this workflow will still run (successfully) on Prs and push only when scheduled and access to the login secrets are avaliable