Automatic merge from submit-queue (batch tested with PRs 42042, 46139, 46126, 46258, 46312)

Remove kubectl's dependence on pkg/api/helper

**What this PR does / why we need it**:

Remove kubectl's dependence on pkg/api/helper, as part of
broader effort to isolate kubectl from the rest of k8s.
In this case, the code becomes private to kubectl; nobody else uses it.

**Which issue this PR fixes**

Part of a series of PRs to address kubernetes/community#598

**Release note**:
```release-note
NONE
```