Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
move cached_discovery to client-go/discovery
**Release note**:
```release-note
NONE
```
Moves the cmd/util CachedDiscoveryClient to client-go
cc @soltysh @deads2k
Kubernetes-commit: f2ea83bef88f9d2783abe0c00de563db13ec04f4
