* User directory
* Fix syncapi unit test
* Make user directory only show remote users you know about from your joined rooms
* Update sytest-whitelist
* Review comments
* Make userapi responsible for checking access tokens
There's still plenty of dependencies on account/device DBs, but this
is a start. This is a breaking change as it adds a required config
value `listen.user_api`.
* Cleanup
* Review comments and test fix