Update PT to TF CLI for audio models
# What does this PR do?

Fixes small issues which prevented converting checkpoints for the whisper model with the pt-to-tf CLI.  

* `"raw_speech"` -> `"audio"`: updates the name of the inputs fed to the processor. This reflects the deprecation of `raw_speech` in [the audio processors](https://github.com/huggingface/transformers/blob/331ea019d7053924ee4d9d4d30282a2c74c272a6/src/transformers/models/wav2vec2/processing_wav2vec2.py#L79)
* Takes the feature extractor's default padding strategy if it's not False. Otherwise sets it to True. This was needed as whisper models must be padded to the max sequence length (not to the max sequence in the batch). Whereas other speech models' feature extractors can run with `padding=True` but don't have max length set by default so will fail if `padding="max_length"` e.g. `"facebook/s2t-small-librispeech-asr"` 


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- [ ] Did you write any new necessary tests?

_The documentation is not available anymore as the PR was closed or merged._<|||||>> This was causing the conversion script to throw exceptions with Whisper, correct?

@gante Exactly. I modified it locally to push the weights to the hub. This PR is a tidier version of the changes I made i.e. not breaking it for other models. 