Add docker compose support and CI workflow for integration tests

[guillermodotn]

Summary

• Add docker compose support to integration tests. Containerfiles now use a configurable REGISTRY_IMAGE build arg via a FROM ... AS stage, and run.sh detects docker compose alongside podman-compose and podman compose.
• Add GitHub Actions workflow to run integration tests on pushes and PRs. Skips gracefully on branches where integration tests don't exist.

[lubomir]

This is really nice. A future improvement would be to bump the fedora image up from 41, as that is EOL already. 44 would be a good candidate.