Feat: Add LCM sampler and DPM++ 2M alt samplers by patching k_diffusion on the fly

[SLAPaper]

Description

• Adding LCM sampler for LCM model and LCM Loras
• Adding DPM++ 2M alt samplers

The implementation code comes from:

• LCM: https://www.bilibili.com/video/BV1TH4y1q7yG/
• DPM++ 2M alt(s): https://github.com/AUTOMATIC1111/stable-diffusion-webui/discussions/8457

Screenshots/videos:

Checklist:

• [x] I have read contributing wiki page
• [x] I have performed a self-review of my own code
• [x] My code follows the style guidelines
• [x] My code passes tests

[FurkanGozukara]

nice. with this one we can directly use LCM LoRAs right?

[continue-revolution]

pls remove LCM sampler for the time being. I am collaborating with the original author and implemented LCM sampler in my AnimateDiff extension, the original author will debug line-by-line until he is satisfied later on. There is another component missing in this PR, regarding LCM sampler.

After he is satisfied, I will submit a PR about LCM sampler.

[bigmover]

pls remove LCM sampler for the time being. I am collaborating with the original author and implemented LCM sampler in my AnimateDiff extension, the original author will debug line-by-line until he is satisfied later on. There is another component missing in this PR, regarding LCM sampler.

After he is satisfied, I will submit a PR about LCM sampler.

Is LCM sampler is available for use Now？

[continue-revolution]

@bigmover update your webui to 1.8.0

[SLAPaper]

Implemented with an extension: https://github.com/SLAPaper/StableDiffusion-dpmpp_2m_alt-Sampler

so close this PR