Support DDIM, PLMS and UNIPC

[AlUlkesh]

@JackeyDeng:

But it does not support DDIM, which file should I modify to support DDIM? I think its almost the same to get DDIM intermediate images, just to decode the intermediate latents?

@AlUlkesh:

When I made that extension, that just wasn't possible with the a1111 infrastructure. You could only get that information from the kdiffusion samplers.

However, I just saw this in the new a1111 release notes:

rework DDIM, PLMS, UniPC to use CFG denoiser same as in k-diffusion samplers

So, perhaps it is possible now. I'll have to look into it.

[AlUlkesh]

I just implemented this. All samplers should now be supported.