Automatic merge from submit-queue (batch tested with PRs 54493, 52501, 55172, 54780, 54819). 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>.

Add CoreDNS as feature in kubeadm

**What this PR does / why we need it**:
This PR adds CoreDNS as a DNS plugin via the feature-gate option in Kubeadm init.

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: 
Fixes kubernetes/features#427

**Special notes for your reviewer**:

**Release note**:

```release-note
kubeadm: Add an experimental mode to deploy CoreDNS instead of KubeDNS
```
/cc @johnbelamaric