feat(kumactl): export in kube format

[jakubdyszkiewicz]

Checklist prior to review

Kumactl export in Kubernetes format.

It converts resources one by one. Obviously, this is not optimal, but my reasoning is

• We would need to introduce new list APIs with two alternative schemas based on query param which is not a great design. We cannot reuse rest.ResourceList for this, because it requires ResourceSpec
• It does not matter if kumactl export will run in 1s or 5s, because it's run once when you do a federation.
• It probably won't be used for backup either, because if you operate on Kubernetes you do a backup on your Kube API Server / etcd level.

We can optimize this if needed.

I plan to write E2E tests when we have applying resources on Zone CP. This way we can test full flow of Zone federation.

• Link to relevant issue as well as docs and UI issues --
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as a image registry) and it will work on Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS --
• Tests (Unit test, E2E tests, manual test on universal and k8s) --
  • Don't forget ci/ labels to run additional/fewer tests
• Do you need to update UPGRADE.md? --
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label) --