Automatic merge from submit-queue (batch tested with PRs 64322, 64210, 64458, 64232, 64370). 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: Add a 'kubeadm config migrate' command
**What this PR does / why we need it**:
This is an UX improvement so users may easier "upgrade" their **configuration files** from the an old version (e.g. `v1alpha1`) version to a new one (e.g. `v1alpha2`), can do this **locally and seamlessly without touching a cluster**. We talked about this in the SIG meeting; getting the users to be able to convert their checked-in configuration files to new API versions will be crucial.
**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
kubeadm: Add a 'kubeadm config migrate' command to convert old API types to their newer counterparts in the new, supported API types. This is just a client-side tool, it just executes locally without requiring a cluster to be running. You can think about this as an Unix pipe that upgrades config files.
```
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