This removes all objects listed in config files (and dependents) -
effectively reversing an `update --create`.

Intended for short-lived "try this out; now clean up" workflows.

Fixes #14

The goal is to make a best-effort attempt at reducing the number of
"crash-restart" loops required to bring up a group of interdependent
resources.

The current implementation is very simple and just sorts into 3 tiers:
- Namespace, ThirdPartyResource, StorageClass
- everything else
- Pods or similar (Pod/Job/Deployment/DaemonSet/StatefulSet)