This commit adds two new global options to kubectl: --profile and
--profile-output, writing out go profiles to disk to debug interesting and
unexpected kubectl behaviour.
As an example, here is how to capture a block file, eg. for how long are we
blocked on I/O and where?
$ kubectl get nodes --profile=mutex -v6
$ go tool pprof -png ./profile.pprof > out.png
$ google-chrome out.png
Fixes: #68679
