Updated code to use a universal Size so we remain cross-platform.

[lushen124]

Some of the Image Codec code was relying on a Windows-specific size structure. We want to keep Yune cross-platform, so we can't use anything that is locked to Windows. We just create a simple Size class that holds an integer width and height, since that seems to be all we need it to hold.

[Geeene]

Oh, I didn't actually realize that was windows only eventhough that win32 in the path should have made that pretty obvious 😅