GitLab

* allow passing op to xFormers attention

original code by @patil-suraj
huggingface/diffusers@ae0cc0b71f28c0f2c5c27026b18f1bea98b505f1

* correct style by `make style`

* add attention_op arg documents

* add usage example to docstring
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* add usage example to docstring
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* code style correction by `make style`

* Update docstring code to a valid python example
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* Update docstring code to a valid python example
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* style correction by `make style`

* Update code exmaple to fully functional
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Suraj Patil <surajp815@gmail.com>