Do not start patch or upgrade if cluster is not healthy and any node is cordoned

[Martin-Weiss]

Is your feature request related to a problem? Please describe.
I want to patch and update the nodes automatically (not just rke2 or k3s but also the operating system) but the upgrade should only start if the health of the cluster is fine and i.e. there are no prometheus alerts or only "some" and in case there is no node cordoned before starting..

Describe the solution you'd like
Allow specification of blocking alerts / whitelist of alerts.
Check cluster health / node status before starting.

This should be a configuration option in the plan..

Describe alternatives you've considered
We have been using kured in the past which can check for actual alerts and also has some sort of reboot control..
https://github.com/weaveworks/kured
Maybe we can integrate some of that?