Support kubectl logs --previous flag

[soenkeliebau]

Kubectl logs has a flag which allows retrieving the logs for an earlier iteration of a pod.

We should also support this and retrieve logs from the previous systemd service that was run for the pod.

Question: would this work across pod boundaries? Not sure when a new invocation id is assigned, what happens when the service crashes and is restarted by systemd, vs the operator deletes the pod and the service is explicitly restarted due to this event?

[lfrancke]

This is waiting for a new Krustlet release (not in 0.7.0).