Set icon also as big winit window icon for increased compatibility.

Under Windows, the big icon is shown at least in the ancient Alt+Tab dialog, which can be restored via registry tweak.

internal/backends/winit/winitwindowadapter.rs

@@ -12,6 +12,7 @@ use std::rc::Weak;
 
 #[cfg(target_arch = "wasm32")]
 use winit::platform::web::WindowExtWebSys;
+use winit::platform::windows::WindowExtWindows;
 
 use crate::renderer::WinitCompatibleRenderer;
 use const_field_offset::FieldOffsets;
@@ -135,7 +136,10 @@ impl WinitWindowOrNone {
 
     fn set_window_icon(&self, icon: Option<winit::window::Icon>) {
         match self {
-            Self::HasWindow(window) => window.set_window_icon(icon),
+            Self::HasWindow(window) => {
+                window.set_window_icon(icon.as_ref().cloned());
+                window.set_taskbar_icon(icon);
+            }
             Self::None(attributes) => attributes.borrow_mut().window_icon = icon,
         }
     }