Scale factor event

[ThatsNoMoon]

Hi hi, enjoying using iced so far.

It would be nice if iced would include an event like winit's ScaleFactorChanged. Since iced seems to handle different scale factors pretty well already, I imagine it wouldn't be too difficult to also send that event to the user. My current use-case is drawing a different icon based on scale factor, as I've found the smaller sizes of the icon need to have higher contrast to stay as legible. Other considerations might include getting the scale factor before the window is open, if possible.

[hecrj]

Sounds reasonable!

It should be fairly easy to add a new window::Event and trigger it from our shells.