Build SCIO as a single, multiprocess image

We have a pending merger of a PR for an AppImage to simplify running ScanCode.io as a command line application but it has a some limitations.

We should also build as a single image that runs all the processes that would then be runnable just using an plain container runner, not compose: this would be a simplified way to distribute and run in Ci/CD.

See https://pulpproject.org/pulp-in-one-container/ and https://docs.pulpproject.org/pulp_oci_images/multi-process-images/

> Multi-Process Images
> These images are also known as "Single Container", or "Pulp in One Container".
> Each image runs all 3 Pulp services (pulp-api, pulp-content and pulp-worker), as well as Pulp's third-party services (nginx, postgresql and redis), in one single container.
> See https://github.com/pulp/pulp-oci-images
>