Skaffold should support pre/post lifecycle hooks for Cleanup

[aaron-prindle]

Issue tracks feature request for skaffold supporting pre/post lifecycle hooks for Cleanup step/phase. This way users could add custom cleanup code as necessary to extend/modify what skaffold does. This would likely involve adding similar UX/functionality to Skaffold's lifecycle pre/post hooks only extended to the Cleanup phase (also would require exposing a Cleanup phase) to allow for this

[netzere]

We have the same use case as well.
Currently we have some pre skaffold script that makes some changes on the target cluster,
and we would like to run another script when stopping skaffold that will revert these cluster changes.

[darth-vader-66]

We have the same use case.