Add Euler Ancestral Discrete Scheduler

[bofeizhu]

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[bofeizhu]

Tested fine with SD 1.5 & 2.0.
Here is an SD 2.0 example with prompt "A cinematic shot of a baby racoon wearing an intricate italian priest robe."
(GS 7.5, Step 25, Seed 1)

However, for some reason, it produces disfigured output with SDXL. Here is an example of the same settings in SDXL.