Automatic merge from submit-queue (batch tested with PRs 49904, 50484, 50214)
Refactor addons into multiple packages
**What this PR does / why we need it**:
https://github.com/kubernetes/kubeadm/issues/348
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
https://github.com/kubernetes/kubeadm/issues/348