Add basic support for resource readiness

[David Desmarais-Michaud]

On a yoke takeoff, resources are created and orphans are removed immediately after.
For many resource types such as Deployments, Pods, StatefulSet, ReplicaSets, and so forth, it would be good to find a mechanism to detect readiness state through their resource status. This way we can prune orphaned resources with more confidence, ie: less chance of downtime.

This could potentially unblock default rollbacks if a yoke takeoff never becomes ready.

Update
As of #20 getting merged, we have basic readiness support for namespaces and custom resource definitions.

This issue becomes about adding logic for other groupkinds such that we could eventually add a --wait flag for yoke takeoff.