[FEATURE] Use podman as fallback for Containerfile/Dockerfile builds when buildah is unavailable

[travier]

Is your feature request related to a problem? Please describe.

In some cases (see redhat-actions/push-to-registry#90), the version of podman installed by default in the Ubuntu 22.04 runners is too old.

To workaround this issue, we can use a custom image. Unfortunately, the podman upstream image does not include buildah (see containers/podman#20771), so we can not use it directly to both build and push an image using actions from this org.

Describe the solution you'd like

For Containerfile/Dockerfile builds, fallback to podman if buildah is not available.

Describe alternatives you've considered

Make a custom image that includes both: https://github.com/travier/podman-action

Additional context

See:

• Add support for signing with Sigstore push-to-registry#90
• podman from Kubic repos (Ubuntu) can not sign using sigstore: Error: initializing private key: decrypt: encrypted: unexpected kdf parameters containers/podman#20771
• https://github.com/travier/cosign-test
• https://github.com/travier/podman-action

[travier]

Another option would be to make another "podman only" action.