Refactor diffusers tasks (#1947)
* refactor diffusers tasks "stable-diffusion" and "stable-diffusion-xl" into "text-to-image", "image-to-image" and "inpainting"
* warn depreated tasks
* generalize diffusion export
* fix
* fix
* fix
* clean up
* trocr
* fix
* standardise model/pipeline mapping task lookup
* add latent consistency
* test
* fix
* fix
* final
* refactor
* fix
* fix offline hub support
* remove unnecessary
* misc
* test
* style
* update docs
