Global scale factor

[lacamar]

It would be useful to have a global scale factor for the app. I use Bluebubbles on a wayland desktop and it's not possible to natively set a custom scale factor for the app. It is only possible by forcing it to use Xwayland which allows for scaling via the GDK_SCALE environmental variable. This is desirable for high DPI displays where the whole app becomes harder to use due to the size.