do-not-merge: Test new on-prem collaborators API
Created by: philipp-spiess
Fixes #32125 (closed)
This is a combination of sg/on-prem-user-invites rebased onto ps/homepage-invite-flow with the APIs properly(?) wired together. Take a look at the last commit only.
Will post the status of this in @slimsag's PR: https://github.com/sourcegraph/sourcegraph/pull/31968