Add Nougat (#25942)
* Add conversion script
* Add NougatImageProcessor
* Add crop margin
* More improvements
* Add docs, READMEs
* Remove print statements
* Include model_max_length
* Add NougatTokenizerFast
* Fix imports
* Improve postprocessing
* Improve image processor
* Fix image processor
* Improve normalize method
* More improvements
* More improvements
* Add processor, improve docs
* Simplify fast tokenizer
* Remove test file
* Fix docstrings
* Use NougatProcessor in conversion script
* Add is_levensthein_available
* Add tokenizer tests
* More improvements
* Use numpy instead of opencv
* Add is_cv2_available
* Fix cv2_available
* Add is_nltk_available
* Add image processor tests, improve crop_margin
* Add integration tests
* Improve integration test
* Use do_rescale instead of hacks, thanks Amy
* Remove random_padding
* Address comments
* Address more comments
* Add import
* Address more comments
* Address more comments
* Address comment
* Address comment
* Set max_model_input_sizes
* Add tests
* Add requires_backends
* Add Nougat to exotic tests
* Use to_pil_image
* Address comment regarding nltk
* Add NLTK
* Improve variable names, integration test
* Add test
* refactor, document, and test regexes
* remove named capture groups, add comments
* format
* add non-markdown fixed tokenization
* format
* correct flakyness of args parse
* add regex comments
* test functionalities for crop_image, align long axis and expected output
* add regex tests
* remove cv2 dependency
* test crop_margin equality between cv2 and python
* refactor table regexes to markdown
add newline
* change print to log, improve doc
* fix high count tables correction
* address PR comments: naming, linting, asserts
* Address comments
* Add copied from
* Update conversion script
* Update conversion script to convert both small and base versions
* Add inference example
* Add more info
* Fix style
* Add require annotators to test
* Define all keyword arguments explicitly
* Move cv2 annotator
* Add tokenizer init method
* Transfer checkpoints
* Add reference to Donut
* Address comments
* Skip test
* Remove cv2 method
* Add copied from statements
* Use cached_property
* Fix docstring
* Add file to not doctested
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Co-authored-by: Pablo Montalvo <pablo.montalvo.leroux@gmail.com>