Update Cluster API to handle kubeadm v1beta2 configuration

[fabriziopandini]

User Story

As a user, I would like Cluster API to support Kubeadm v1beta2 config as part of KubeadmConfig and KubeadmControlPlane because the v1beta1 configuration is deprecated and will eventually lose support.

Detailed Description
Kubeadm is deprecated, and while there is not yet a date for removal, we should start to plan for starting to use v1beta2 in cluster API.

The issue is complicated by the fact that there is not yet agreement on k/k on how to handle component config upgrade and, as a consequence, kubeadm is not offering an automatic conversion func.
This is also relate to the work of moving kubeadm out of k/k and make it usable as a library (currently on hold 😞 ).

/kind feature

[vincepri]

/milestone Next

Unfortunately we'll have to tackle this item in v1alpha4 given that we might need breaking changes and/or a redesign of the current APIs.

[vincepri]

Closing this in favor of #3150

/close

[k8s-ci-robot]

@vincepri: Closing this issue.

In response to this:

Closing this in favor of #3150

/close

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[Arvinderpal]

@vincepri

Closing this in favor of #3150

/close

@vincepri Did you mean to reference some other issue or was this closed by accident?

[vincepri]

It should have been closed in favor of #2769