Checkpoint/Restore KEP ready for review (#2008)

[Adrian Reber]

As discussed in today's sig-node meeting I updated the
checkpoint/restore KEP (#2008)

https://github.com/kubernetes/enhancements/pull/1990

to include the forensic use case (User Story 1) and I tried
to make it clear that the goal of the KEP for 1.23 is to
introduce checkpoint/restore in small steps.

For the proposed forensic use case that would be the CRI API extension
to allow the container engine to provide checkpoint/restore primitives
as well as minimal kubelet changes to trigger a checkpoint.

Only checkpointing is currently the goal for the forensic use case with
the option to restore the container outside of Kubernetes somewhere else
for forensic analysis.

Please let me know if anything is missing from the KEP. Thanks.

Adrian