R1:9af376a74356

Add a setup warning for calls to deprecated Conduit methods

Summary: We probably can't land this yet, since `arc tasks` still uses `maniphest.find` and `arc close` still uses `differential.getrevision`. We should clean those up and wait at least 30 days before committing this (maybe).

Test Plan: Saw setup issues for `maniphest.find` and `differential.getrevision` calls.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley, joshuaspence, FacebookPOC, aran

Differential Revision: https…