Allow custom icon from whitelabel design in desktop app

[Pa7Hub]

Change so that a set whitelabel design / logo will also change the icon of the desktop app.

[paw-hub]

~~This seems to already be the case. Maybe it was fixed already?~~

Nevermind, I think you were actually referring to the icon shown on the desktop itself rather than the logo/icon in the app. I wonder how this will handle multiple instances of the app? For example, you might be signed in on a whitelabel account on one instance and a private account on another instance.