In debugging what's going on with the Elixir language server, there was
some interesting content in the server's logs (sent to the app via the
`window/logMessage` LSP endpoint). I decided to invest in making
language server issues easier to debug by exposing these `logMessage`
contents in the app.

Also, improve the UI of the view slightly:

* Select one of the servers by default (instead of "no server selected")
* Make it clearer that the menu is clickable