* Adding isNodeDeleted method to CloudProvider interface. Supports detecting whether nodes are fully deleted or are not-autoscaled. Updated cloud providers to provide initial implementation of new method that will return an ErrNotImplemented to maintain existing taint-based deletion clusterstate calculation.
This is the first step of implementing
https://github.com/kubernetes/autoscaler/issues/3583#issuecomment-743215343.
New method was added to cloudprovider interface. All existing providers
were updated with a no-op stub implementation that will result in no
behavior change.
The config values specified per NodeGroup are not yet applied.