R1:27d426e3fe92

Allow Conduit console to be browsed by logged-out users

Summary:
Ref T4830. A few methods, like `conduit.ping`, are callable without authentication, so this even has some use cases. Also:

- Make some Differential stuff a little more consistent.
- Use slightly more modern rendering.
- Deprecate the status-oriented `user` calls; these will be replaced by Calendar methods.

Test Plan: Browsed console as logged out / logged in users.

Reviewers: chad, btrahan

Reviewed By: btrahan

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