complete kube module

[jam01]

• support label selectors
• document supported arguments
• refactor retry to be command specific
• provide diff functionality
• provide check mode
• return changed appropriately

see: https://github.com/fluxcd/kustomize-controller/blob/v0.11.1/controllers/utils.go#L30
https://github.com/fluxcd/kustomize-controller/blob/v0.11.1/controllers/kustomization_controller.go#L363