Automatic merge from submit-queue (batch tested with PRs 67776, 67503, 67679, 67786, 67830). 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>.
kubeadm config move ControlPlaneEndpoint to ClusterConfiguration
**What this PR does / why we need it**:
This PR moves `ControlPlaneEndpoint` from the `API` config struct to `ClusterConfiguration`.
This change is required as initial step for enabling management of more than one control plane instances in kubeadm
**Which issue(s) this PR fixes** :
refs https://github.com/kubernetes/kubeadm/issues/911, refs https://github.com/kubernetes/kubeadm/issues/963
**Special notes for your reviewer**:
just an appetizer, the main dish will be the next PR...
**Release note**:
```release-note
kubeadm: ControlPlaneEndpoint was moved from the API config struct to ClusterConfiguration
```
/cc @kubernetes/sig-cluster-lifecycle-pr-reviews
/sig cluster-lifecycle
/area kubeadm
/kind api-change
/kind enhancement
/assign @luxas
/assign @timothysc
/cc @chuckha @rosti @neolit123 @liztio