Allow pop-up to be default or have a button on the main window to turn it on

**Describe the feature you want:**
I would like a way to either make the Pop-up mode the default, so that when you click on the extension, the window with the code opens in the pop-up window mode every time
Alternatively, a button on the title bar (when the Settings, Lock, Scan and Edit buttons are), to switch to pop-up mode with one click.

**Why do you want this feature in Authenticator?**
I use Google authentication to secure sshd on servers. If I open the Authenticator extension to get a code and then click into my terminal windows, the extension closes immediately & I can't see the code to type it into my terminal, which is really frustrating.
If there was a way to keep the code on screen when you switch focus to another program, it would make this extension far more usable. I assume you can't keep the normal extension window from closing as soon as Chrome loses focus and that's why you created the pop-up mode, However it's too clunky to have to click on Settings, Preferences, Popup mode to enable it each time you want a code.
Otherwise this is great extension - thanks for creating it :-)

Empieza rastreando el comportamiento al hacer clic en la extensión y el flujo de Settings > Preferences > Popup mode. Decide cómo encaja en la UI existente la acción solicitada predeterminada o de un clic en la barra de título; se considera terminado cuando el código sigue visible después de cambiar a una terminal u otro programa sin tener que activar repetidamente el modo popup.

Escrito por el modelo de indexación a partir del texto del issue.