Fast image processor (#28847)

* Draft fast image processors

* Draft working fast version

* py3.8 compatible cache

* Enable loading fast image processors through auto

* Tidy up; rescale behaviour based on input type

* Enable tests for fast image processors

* Smarter rescaling

* Don't default to Fast

* Safer imports

* Add necessary Pillow requirement

* Woops

* Add AutoImageProcessor test

* Fix up

* Fix test for imagegpt

* Fix test

* Review comments

* Add warning for TF and JAX input types

* Rearrange

* Return transforms

* NumpyToTensor transformation

* Rebase - include changes from upstream in ImageProcessingMixin

* Safe typing

* Fix up

* convert mean/std to tesnor to rescale

* Don't store transforms in state

* Fix up

* Update src/transformers/image_processing_utils_fast.py

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* Update src/transformers/models/auto/image_processing_auto.py

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* Update src/transformers/models/auto/image_processing_auto.py

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* Update src/transformers/models/auto/image_processing_auto.py

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>

* Warn if fast image processor available

* Update src/transformers/models/vit/image_processing_vit_fast.py

* Transpose incoming numpy images to be in CHW format

* Update mapping names based on packages, auto set fast to None

* Fix up

* Fix

* Add AutoImageProcessor.from_pretrained(checkpoint, use_fast=True) test

* Update src/transformers/models/vit/image_processing_vit_fast.py

Co-authored-by: Pavel Iakubovskii <qubvel@gmail.com>

* Add equivalence and speed tests

* Fix up

---------

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: Pavel Iakubovskii <qubvel@gmail.com>

docs/source/en/model_doc/vit.md

@@ -62,7 +62,7 @@ Following the original Vision Transformer, some follow-up works have been made:
 This model was contributed by [nielsr](https://huggingface.co/nielsr). The original code (written in JAX) can be
 found [here](https://github.com/google-research/vision_transformer).
 
-Note that we converted the weights from Ross Wightman's [timm library](https://github.com/rwightman/pytorch-image-models), 
+Note that we converted the weights from Ross Wightman's [timm library](https://github.com/rwightman/pytorch-image-models),
 who already converted the weights from JAX to PyTorch. Credits go to him!
 
 ## Usage tips
@@ -158,6 +158,11 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 [[autodoc]] ViTImageProcessor
     - preprocess
 
+## ViTImageProcessorFast
+
+[[autodoc]] ViTImageProcessorFast
+    - preprocess
+
 <frameworkcontent>
 <pt>