Wav2Vec2 meets phonemes
# What does this PR do?

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This PR adds Wav2Vec2 with Phoneme support and adds the checkpoints of https://arxiv.org/abs/2109.11680 (See last table: https://github.com/pytorch/fairseq/tree/main/examples/wav2vec#pre-trained-models)

The speech recognition script is adapted and tested to be sure phoneme recognition works as expected. See:
https://huggingface.co/patrickvonplaten/wav2vec2-xls-r-phoneme-300m-tr
and 
https://huggingface.co/patrickvonplaten/wav2vec2-xls-r-phoneme-300m-sv


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Models:

- albert, bert, xlm: @LysandreJik
- blenderbot, bart, marian, pegasus, encoderdecoder,  t5: @patrickvonplaten, @patil-suraj
- longformer, reformer, transfoxl, xlnet: @patrickvonplaten
- fsmt: @stas00
- funnel: @sgugger
- gpt2: @patrickvonplaten, @LysandreJik
- rag: @patrickvonplaten, @lhoestq
- tensorflow: @LysandreJik

Library:

- benchmarks: @patrickvonplaten
- deepspeed: @stas00
- ray/raytune: @richardliaw, @amogkam
- text generation: @patrickvonplaten
- tokenizers: @n1t0, @LysandreJik
- trainer: @sgugger
- pipelines: @LysandreJik

Documentation: @sgugger

HF projects:

- datasets: [different repo](https://github.com/huggingface/datasets)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Examples:

- maintained examples (not research project or legacy): @sgugger, @patil-suraj
- research_projects/bert-loses-patience: @JetRunner
- research_projects/distillation: @VictorSanh

 -->

Failing tests are unrelated.<|||||>Model can be advertised  next week with author<|||||>> Thanks for adding this. I'm not following why there is a new entry for XLS-R which doesn't get its model folder or its model type in the config mapping.

Yeah I'm adding XLS-R to give it a bit more visibility (similar to how we have [DialoGPT](https://huggingface.co/docs/transformers/model_doc/dialogpt) and XLSR-Wav2Vec2 in the docs even though they have 0 added code). Think a lot of people do decide on which checkpoints to use depending on the docs so I think it's good to add more information to the docs. 

Happy to revert it though if you guys prefer<|||||>I'm getting an error when running the tests locally:
```
ɛ l o h aʊ a ʁ j u != ɛ l o h a w a ʁ j u

Expected :ɛ l o h a w a ʁ j u
Actual   :ɛ l o h aʊ a ʁ j u
<Click to see difference>

Traceback (most recent call last):
  File "/home/lysandre/transformers/tests/test_tokenization_wav2vec2_phoneme.py", line 214, in test_change_phonemizer_lang
    self.assertEqual(text_fr, "ɛ l o h aʊ a ʁ j u")
AssertionError: 'ɛ l o h a w a ʁ j u' != 'ɛ l o h aʊ a ʁ j u'
- ɛ l o h a w a ʁ j u
?          ^^
+ ɛ l o h aʊ a ʁ j u
?          ^


```<|||||>> I'm getting an error when running the tests locally:
> 
> ```
> ɛ l o h aʊ a ʁ j u != ɛ l o h a w a ʁ j u
> 
> Expected :ɛ l o h a w a ʁ j u
> Actual   :ɛ l o h aʊ a ʁ j u
> <Click to see difference>
> 
> Traceback (most recent call last):
>   File "/home/lysandre/transformers/tests/test_tokenization_wav2vec2_phoneme.py", line 214, in test_change_phonemizer_lang
>     self.assertEqual(text_fr, "ɛ l o h aʊ a ʁ j u")
> AssertionError: 'ɛ l o h a w a ʁ j u' != 'ɛ l o h aʊ a ʁ j u'
> - ɛ l o h a w a ʁ j u
> ?          ^^
> + ɛ l o h aʊ a ʁ j u
> ?          ^
> ```

Hmm interesting - what does:

```bash
python -c "import phonemizer; print(phonemizer.__version__)"
```
give you? 

and is it on Windows ? Or Ubuntu?<|||||>On an arch-based distro, returns `3.0`!

And `espeak --version` returns
```
eSpeak text-to-speech: 1.48.03  04.Mar.14  Data at: /usr/share/espeak-data
```<|||||>> espeak --version

Hmm, interesting. I think the library to be installed should be `espeak-ng` however as stated here: https://github.com/bootphon/phonemizer#dependencies

Could you try one last thing:

```bash
sudo apt-get install espeak-ng
```

which should give version:

```
eSpeak NG text-to-speech: 1.50
```

and try the test again.<|||||>Thank you for showing me the way, installing with `espeak-ng` passes all test! 