Refactor `pkg/test/utils/kubernetes.go`

<!-- Please only use this template for submitting enhancement requests. Implementing your enhancement will follow the KEP process: https://github.com/kudobuilder/kuttl/blob/main/keps/0001-kep-process.md --> **What would you like to be added**: A new package `pkg/kubernetes/`. **Why is this needed**: `pkg/test/utils/kubernetes.go` has grown huge and we should refactor it to a separate package. Reference discussion: https://github.com/kudobuilder/kuttl/pull/576#discussion_r1859982831 cc: @porridge