Add TFHubertModel
Author: will-rice
Pull request: yes

# What does this PR do?
This PR adds the TFHubert Model.
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Fixes # (issue)


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Comments:
Hey @will-rice,

Wow that was quick! :D Can you remove the [WIP] whenever the PR is ready for review? :-)

One thing that's different from the PyTorch version is I couldn't use the copy comments because I added the type to the config arguments in Wav2Vec2. If I retained the copy comments it would overwrite HubertConfig with Wav2Vec2Config. Which makes sense, but I wondered if there was a way to fix this so I could keep the copy comments, but ignore the config type.

I added back the WIP based on the TFWav2Vec2 [bugs](https://github.com/huggingface/transformers/issues/12264#issuecomment-864611327). I will update this with the fixes when those are corrected. 

@patrickvonplaten I believe this one is ready for review now. I updated it with the wav2vec2 bug fixes.

@patrickvonplaten I can definitely add the copy comments. The issue I ran into was due to Wav2Vec2Config typing in TFWav2Vec2 so the copy script overwrites the TFHubertConfig. I didn't look in depth at the copy code, but I was thinking that we could allow the copy to ignore typing.

Removing the config typing from TFWav2Vec2 would work though and that's how it is in PyTorch.

> Removing the config typing from TFWav2Vec2 would work though and that's how it is in PyTorch.

Ah you can add something like `with Wav2Vec2->Hubert` which should correctly replace the class name when copying

Left a comment here: https://github.com/huggingface/transformers/pull/12206/files?file-filters%5B%5D=.py#r667074787 :-) That's how it should work well with the configs

> Left a comment here: https://github.com/huggingface/transformers/pull/12206/files?file-filters%5B%5D=.py#r667074787 :-) That's how it should work well with the configs

🤦‍♂️ 

Thanks! I will update it now.