The lobby feature adds the possibility to lock a meeting and only allow people in after virtually knocking and going through formal approval

* Add dialog to set the E2EE key
* Use the Redux action / middleware to update the key even when set through the
  hash parameter
* Cleanup URL after processing the key so it's not recorded in browser history

React Native doesn't define __filename nor __dirname so do it artisanally. In
addition, this helps with centralizing the configuration passed to loggers.