Summary:
Connections from VSCode and Kite would remain forever pending because they don't go through the secure connection handler. This diff fixes that. Also removed the separate event that existed for that, since registering a new client is already a 'success' signal, so it doesn't need a separate event.
It turned out that the VSCode pending connection is actually correct, as it never handles the `getPlugins` event, so apparently the handling is broken. Added timeouts to guard against that as well.
Applied several code simplications as well.
Introduced an explicit cert exchange medium 'NONE' so that in code it is a bit clearer where CSR negotiation is supposed to happen.
Changelog: Fixed an issue where Kite / Unity apps didn't connect anymore
Reviewed By: timur-valiev
Differential Revision: D30866301
fbshipit-source-id: 8bd214fd9eebcd9a7583f1b44ee283883002f62e