[Whisper] Computing features on GPU in batch mode for whisper feature extractor. (#29900)
* add _torch_extract_fbank_features_batch function in feature_extractor_whisper
* reformat feature_extraction_whisper.py file
* handle batching in single function
* add gpu test & doc
* add batch test & device in each __call__
* add device arg in doc string
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Co-authored-by: vaibhav.aggarwal <vaibhav.aggarwal@sprinklr.com>