Re: [PoC] Federated Authn/z with OAUTHBEARER

Hi all,

v3 rebases this patchset over the top of Samay's pluggable auth
provider API [1], included here as patches 0001-3. The final patch in
the set ports the server implementation from a core feature to a
contrib module; to switch between the two approaches, simply leave out
that final patch.

There are still some backend changes that must be made to get this
working, as pointed out in 0009, and obviously libpq support still
requires code changes.

--Jacob

[1] https://www.postgresql.org/message-id/flat/CAJxrbyxTRn5P8J-p%2BwHLwFahK5y56PhK28VOb55jqMO05Y-DJw%40mail.gmail.com