Handle PersistenVolumeClaimTemplate defined by EphemeralVolumeSource

[flavio]

The Volume resource has an attributed called ephemeral of type EphemeralVolumeSource, which has inside of itself the volumeClaimTemplate of type VolumeClaimTemplate. The PersistentVolumeClaimTemplate can reference a storageClass. This is the same type of object defined inside of StatefulSet.spec.persistentVolumeClaimTemplates (see #1).

The policy should be extended to look also inside of the podSpec.volumes.*.ephemeral.volumeClaimTemplate.spec.storageClassName. Given podSpec are embedded into higher level Kubernetes resources; the policy should be capable of inspecting Pod, Deployment, CronJob, StatefulSet.

When inspecting StatefulSet objects, we have to be careful because the PVC can be defined in two places: inside of the podSpec (with this convoluted series of objects) and also inside of volumeClaimTemplates (which is handled by #1).

Configuration

The configuration settings of the policy do not need to be changed. They are going to be applied in the same way