Upsampling Guidance

this is unoffical implement for the paper Upsample Guidance: Scale Up Diffusion Models without Training

example code in tmp.py, currently only implement for Stable Diffusion 1.5, results looks good for a free launch method.

SDXL code will be later.

Part of results

left is SD15 generate 1024x1024 image, right is SD15 with upsampling guidance generated 1024x1024 image