Previously, api_key_only_webhook_view passed 3 positional arguments
(request, user_profile, and client) into a function. However, most
of our other auth decorators only pass 2 positional arguments. For
the sake of consistency, we now make api_key_only_webhook_view set
request.client and pass only request and user_profile as positional
arguments.
We now show a few new things:
(1) The number of commits pushed.
(2) Who authored the commits (just counts, not which specific ones, for brevity).
Add tests for case of multiple committers.
Part of #3968.