Add podman service to start all containers with restart policy set to Always

Upstream podman comes with systemd service that automatically starts all containers that have a restart policy set to Always: https://github.com/containers/podman/blob/main/contrib/systemd/system/podman-restart.service.in

This allows to mimic Docker's behavior, which does the same.

Since Alpine ships podman with own init scripting, this functionality is not reproduced.