Add support for running compute worker with other container engines

A brief description of the purpose of the changes contained in this PR.

This PR adds a new configuration environment variable (CONTAINER_ENGINE_EXECUTABLE) to allow the compute worker to be run with other container technology such as podman. It also provides a rootless podman Containerfile.

Issues this PR resolves

Allow computer worker to run with podman

Checklist

• Code review by me
• Hand tested by me
• I'm proud of my work
• Code review by reviewer
• Hand tested by reviewer
• Ready to merge