Add support for different model prediction types in DDIMInverseScheduler (#2619)
* Add support for different model prediction types in DDIMInverseScheduler
Resolve alpha_prod_t_prev index issue for final step of inversion
* Fix old bug introduced when prediction type is "sample"
* Add support for sample clipping for numerical stability and deprecate old kwarg
* Detach sample, alphas, betas
Derive predicted noise from model output before dist. regularization
Style cleanup
* Log loss for debugging
* Revert "Log loss for debugging"
This reverts commit 76ea9c856f99f4c8eca45a0b1801593bb982584b.
* Add comments
* Add inversion equivalence test
* Add expected data for Pix2PixZero pipeline tests with SD 2
* Update tests/pipelines/stable_diffusion/test_stable_diffusion_pix2pix_zero.py
* Remove cruft and add more explanatory comments
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Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>