[Win32] Properly reinitialize image of items on DPI changes

The current logic for reinitializing the image of an item on DPI changes
is insufficient as the default implementation of the called setImage()
method and many of the overwrites of that method do an early return in
case the image equals to the one that has already been set.

In order to force a reinitialization of the image, this change ensures
that the image is first removed and then reset.

Fixes #3073

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT/common/org/eclipse/swt/widgets/Item.java

@@ -230,6 +230,7 @@ private void handleDPIChange(Event event) {
 	// Refresh the image
 	Image image = getImage();
 	if (image != null) {
+		setImage(null);
 		setImage(image);
 	}
 }