Allow for filtering kubectl apply results based on result (created, updated, no change)

[Niksko]

Currently, the notifications that are sent from the kustomize controller contain all the resources processed by the kustomization. When there are large numbers of resources, the unchanged resources overwhelm the notification body, when all we care about are the updated and created resources.

It would be good to be able to filter the notifications that were sent based on whether the result of the kubectl apply was a create, and update, or no change