Add support for parsing OWNERS files

[medyagh]

in miniukube's triage-party, I added a user to the reviwers in OWNERS file and I saw he had responded to an isssue and labeled too, but the triage party still was saying issues without comment, till I commented

example kubernetes/minikube#8460

[tstromberg]

In addition to the members section in the Triage Party, what do you think about an additional members-from declaration, that allows a file and/or URL?

members-from: https://raw.githubusercontent.com/kubernetes/minikube/master/OWNERS

Initially it would just support https://go.k8s.io/owners format (map[string][]string)- but could be expanded to support other formats.