Add tooltips to Conphrence Chatroom switcher icons

Summary: I don't know the names of all the Conpherences I have ongoing and all my test icons are Psyducks. haha ha ...

Test Plan: Hover over icons, now it's all Psyduck and [No Title].

Reviewers: epriestley, btrahan

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D12050