As a preliminary work to MULTIARCH-4970, the operands should be able to have a cache of the ClusterPodPlacementConfig through an informer.

Acceptance Criteria:

• An informer is implemented in a package shared by both the controller and webhook to track changes to the ClusterPodPlacementConfig
• The informer is added to the manager if a parameter, --enable-cluster-pod-placement-config-informer, is set to true
• The informer should implement the onAdd and onUpdate event handlers to store the cluster pod placement config and keep it up-to-date.