Please Add a Fast Flaubert_tokenizer class as well to leverage fast_tokenizer methods
### System Info

transformers version: 4.20.1
GPU: Nvidia Titan T4



### Who can help?

@LysandreJik I feel that you can help best since Flaubert Tokenizer class is directly inherited from XLM's Tokenizer which also does not have a fast tokenizer class too!



### Information

- [x] My own modified scripts
- [ ] The official example scripts

### Tasks

- [ ] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [X] My own task or dataset (give details below)

### Reproduction


This method is not working since my AutoTokenizer Class is taking the default FlaubertTokenizer class and since we don't have a Flaubert_tokenizer_fast class here; we are not able to leverage fast_tokenizer functionalities!
<img width="1245" alt="Screenshot 2022-07-14 at 4 39 38 PM" src="https://user-images.githubusercontent.com/78647606/179044514-e6081be4-591a-48bb-bf10-56ab90628ab0.png">


### Expected behavior

If FlaubertTokenizer has a faster version class like BertToeknizerFast; We will be able to use class methods like word_ids, word_to_tokens, etc Specifically for the TokenClasssifcation task.
This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

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