[Whisper] Add SpecAugment (#21298)

* Return and rescale attention_mask

* Add SpecAugment to Whisper modeling

* Fix test

* Update docstring

* Add SpecAug related parameters to model config

* Add the _mask_input_features function to doc

* Fix quality

* Apply suggestions from code review

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

* Remove dev comments

* Add test

* Resolve conflict

* feat: mask {feature, time} prob fast tests

* Apply suggestions from code review

Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

---------

Co-authored-by: Arthur <48595927+ArthurZucker@users.noreply.github.com>
Co-authored-by: sanchit-gandhi <sanchit@huggingface.co>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

docs/source/en/model_doc/whisper.mdx

@@ -72,6 +72,7 @@ The original code can be found [here](https://github.com/openai/whisper).
 
 [[autodoc]] WhisperModel
     - forward
+    - _mask_input_features
 
 ## WhisperForConditionalGeneration