Automatic merge from submit-queue

Fail kubelet creation if swap enabled and configured with memory eviction thresholds

/cc @vishh @derekwaynecarr

**Release note**:

```
This adds an opt-in Kubelet flag (--fail-swap-on) that causes the Kubelet to fail to start if swap is enabled on the node. This is a temporary opt-in, and the Kubelet will by default fail with swap enabled starting in 1.6.0. The KubeletConfiguration equivalent to the flag is FailSwapOn.
```