for users to interact with this feature we need to add a field in the ClusterAutoscaler API resource.

ideally, the field should be named `CordonNodeBeforeTerminating` and be part of the `Spec.ScaleDown` field. it would be nice to use a discriminated union instead of a boolean, with the values "enabled" and "disabled". using a union instead of a boolean allows for better validation through the kubebuilder annotations, and better options for detecting unset zero values in the api.

For an example of how to add a new field to the ClusterAutoscaler resource, please see https://github.com/openshift/cluster-autoscaler-operator/pull/304