Add support for Pixtral (#33449)

* initial commit

* gloups

* updates

* work

* weights match

* nits

* nits

* updates to support the tokenizer :)

* updates

* Pixtral processor (#33454)

* rough outline

* Add in image break and end tokens

* Fix

* Udo some formatting changes

* Set patch_size default

* Fix

* Fix token expansion

* nit in conversion script

* Fix image token list creation

* done

* add expected results

* Process list of list of images (#33465)

* updates

* working image and processor

* this is the expected format

* some fixes

* push current updated

* working mult images!

* add a small integration test

* Uodate configuration docstring

* Formatting

* Config docstring fix

* simplify model test

* fixup modeling and etests

* Return BatchMixFeature in image processor

* fix some copies

* update

* nits

* Update model docstring

* Apply suggestions from code review

* Fix up

* updates

* revert modeling changes

* update

* update

* fix load safe

* addd liscence

* update

* use pixel_values as required by the model

* skip some tests and refactor

* Add pixtral image processing tests (#33476)

* Image processing tests

* Add processing tests

* woops

* defaults reflect pixtral image processor

* fixup post merge

* images -> pixel values

* oups sorry Mr docbuilder

* isort

* fix

* fix processor tests

* small fixes

* nit

* update

* last nits

* oups this was really breaking!

* nits

* is composition needs to be true

---------

Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>

docs/source/en/index.md

@@ -253,6 +253,7 @@ Flax), PyTorch, and/or TensorFlow.
 |                          [Phi3](model_doc/phi3)                          |       ✅        |         ❌         |      ❌      |
 |                       [PhoBERT](model_doc/phobert)                       |       ✅        |         ✅         |      ✅      |
 |                    [Pix2Struct](model_doc/pix2struct)                    |       ✅        |         ❌         |      ❌      |
+|                       [Pixtral](model_doc/pixtral)                       |       ❌        |         ❌         |      ❌      |
 |                        [PLBart](model_doc/plbart)                        |       ✅        |         ❌         |      ❌      |
 |                    [PoolFormer](model_doc/poolformer)                    |       ✅        |         ❌         |      ❌      |
 |                     [Pop2Piano](model_doc/pop2piano)                     |       ✅        |         ❌         |      ❌      |