This partially reverts eec6a270.

The problem is that when a conference is protected by a password or has
auth enabled, the "joined" event will come later, when the user
authenticates, so the 10s timeout will kick in.

This is not ideal because we react to the onLoad event of an iframe,
which doesn't tell us much of *what* is actually loaded, but a new event
would be required to properly fix this.

This is the new syntax for extending components. See:
https://github.com/styled-components/styled-components/issues/1546

Fixes: https://github.com/jitsi/jitsi-meet-electron/issues/124

Wait until the joined event.

Also, create a couple of auxiliary functions so we save some indentation
in the main render function.

Fixes: https://github.com/jitsi/jitsi-meet-electron/issues/103



Co-authored-by: Akshit Kr Nagpal <akshitkrnagpal@gmail.com>