Add WhisperTokenizerFast (#21222)

* Add WhisperTokenizerFast

* Fixup

* Up

* Up

* Improve tests

* Update src/transformers/models/whisper/tokenization_whisper_fast.py

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

* Keep stride in whisper pipelien test

* Remove unknown token special case

* Reduce vocabulary size in tests

* Fix vocab size assertion

* Sync copied changes from WhisperTokenizer

* Skip pipeline tests

* Update assertion

* Remove Whisper tokenizer dependency on sentencepiece

* Format

---------

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

docs/source/en/model_doc/whisper.mdx

@@ -45,6 +45,15 @@ The original code can be found [here](https://github.com/openai/whisper).
     - create_token_type_ids_from_sequences
     - save_vocabulary
 
+## WhisperTokenizerFast
+
+[[autodoc]] WhisperTokenizerFast
+    - set_prefix_tokens
+    - build_inputs_with_special_tokens
+    - get_special_tokens_mask
+    - create_token_type_ids_from_sequences
+    - save_vocabulary
+
 ## WhisperFeatureExtractor
 
 [[autodoc]] WhisperFeatureExtractor