Support for the "same" team across different orgs

**What would you like to be added**:
In GitHub (at least GitHub Enterprise), `Teams` cannot be cross-org. I would like to support cross-org "Teams".

**Why is this needed**:
To "get around" the problem, we just replicate the same teams across different orgs. It would be nice to _reference_ a `Team`, with like `teamRef` or something, that is specified at the `Orgs` level so they can be reused.

Start by reviewing the Kubernetes org repository's existing organization and team configuration entry points. The issue names no files or tests, so identify how teams are currently represented and referenced across organizations before defining the cross-organization team reference behavior. Done means the desired shared-team model is implemented and validated for the relevant organization configurations.

Written by the indexing model from the issue text.