Summary:
Ref T5955.
- Add `conduit.getcapabilities` to help arc (and other clients) determine formats, protocols, etc., the server supports.
- Fixes T3117. Add a more modern version of the handshake workflow that allows all generated tokens to remain valid for an hour.
- Generally, add a CLI token type. This token type expires after an hour when generated, then becomes permanent if used.
Test Plan:
- See D10988.
- Ran `conduit.getcapabilities` and inspected output.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T3117, T5955
Differential Revision: https://secure.phabricator.com/D10989
