Button to reconnect to the server

Unfortunately the connection I have during the day drops quite often on my PC, this has caused Keybase not to reconnect and me to miss messages more than once, a button could really solve this.

Start by tracing the desktop client's connection and reconnect flow, since the issue names no files, tests, or entry points. Determine where a reconnect control belongs and define done as a user-triggered reconnect that restores message delivery after a dropped connection.

Written by the indexing model from the issue text.