Detect conditions when workers need to be restarted or re-joined

[kke]

As mentioned by @twz123 in #721 (comment) - there are situations that could be consistently detected by k0sctl that require that the existing workers are restarted / reconfigured / rejoined.

This is something k0sctl should handle gracefully.

[kke]

First and the most obvious is the change of externalAddress when a new token needs to be generated as the address is inside the token.

So, if that is detected, the service on the worker needs to be stopped, the two kubelet auth files need to be deleted and then a reinstall performed (which can be the regular InstallWorkers phase that now thinks there is no k0s).