[Feature request] Add swin_unet models for waifu2x

[Collect-diamond]

swin_unet models for waifu2x on unlimited:waifu2x, and its currently not in this gui app(only upconv 7 and cunet).

[AaronFeng753]

Thank you for your suggestion, I will check it out

[AaronFeng753]

Just tested the new model, hardly any difference compare to the old cunet model, sometimes even a bit worse

So why not just use the already built-in real-cugan engine

I will see what I can do about it when I got more time