* Adds a dropdown indicator which displays the status of the internet connection.
* It uses the same data as `https://network.callstats.io`.
* The algorithm for the strings displayed to the user is also the one used on `network.callstas.io`.

A user should not be forced to enter a display name if the lobby is not enabled
for the room.

* Add a checkbox for skipping the prejoin page on next use. (This is hidden for
now, until we also have a settings entry for it).
* Rework 'Join by Phone' buttons and add new overlay.
* Update the device status accordingly if there were errors while adding
devices.
* The input is filled with the display name if there was one previously used.
* Join the meeting on 'Enter' press.