[WIP] Return local paths to Common Voice

Fixes https://github.com/huggingface/datasets/issues/3663

This is a proposed way of returning the old local file-based generator while keeping the new streaming generator intact.

TODO:
- [ ] brainstorm a bit more on https://github.com/huggingface/datasets/issues/3663 to see if we can do better
- [ ] refactor the heck out of this PR to avoid completely copying the logic between the two generators

Cool thanks for giving it a try @anton-l ! 

Would be very much in favor of having "real" paths to the audio files again for non-streaming use cases. At the same time it would be nice to make the audio data loading script as understandable as possible so that the community can easily add audio datasets in the future by looking at this one as an example. Think if it's clear for a contributor how to add an audio datasets script that works for the standard non-streaming case while it is easy to extend it afterwards to a streaming dataset script, then this would be perfect

@anton-l @patrickvonplaten @lhoestq Is it possible somehow to provide this logic inside the library instead of a loading script so that we don't need to completely rewrite all the scripts for audio datasets and users don't have to care about two different loading approaches in the same script? 🤔   

> @anton-l @patrickvonplaten @lhoestq Is it possible somehow to provide this logic inside the library instead of a loading script so that we don't need to completely rewrite all the scripts for audio datasets and users don't have to care about two different loading approaches in the same script? thinking

Not sure @lhoestq - what do you think? 

Now that we've corrected the previous resampling bug, think this one here is of high importance. @lhoestq - what do you think how we should proceed here? 

> @anton-l @patrickvonplaten @lhoestq Is it possible somehow to provide this logic inside the library instead of a loading script so that we don't need to completely rewrite all the scripts for audio datasets and users don't have to care about two different loading approaches in the same script? 🤔

Yes let's do this :)

Maybe we can change the behavior of `DownloadManager.iter_archive` back to extracting the TAR archive locally, and return an iterable of (local path, file obj). And the `StreamingDownloadManager.iter_archive` can return an iterable of (relative path inside the archive, file obj) ?

In this case, a dataset would need to have something like this:
```python
for path, f in files:
    yield id_, {"audio": {"path": path, "bytes": f.read() if not is_local_file(path) else None}}
```

Alternatively, we can allow this if we consider that `Audio.encode_example` sets the "bytes" field to `None` automatically if `path` is a local path:
```python
for path, f in files:
    yield id_, {"audio": {"path": path, "bytes": f.read()}}
```
Note that in this case the file is read for nothing though (maybe it's not a big deal ?)

Let me know if it sounds good to you and what you'd prefer !

@lhoestq I'm very much in favor of your first aproach! With the full paths returned I think we won't even need to mess with `os.path.join` vs `"/".join()"` and other local/streaming differences 👍 

@lhoestq I also like the idea and favor your first approach to avoid an unnecessary read and make yielding faster.

Looks cool - thanks for working on this. I just feel strongly about `path` being an absolute `path` that exist and can be inspected in the non-streaming case :-) For streaming=True IMO it's absolutely fine if we only have access to the bytes

Hi ! I started implementing this but I noticed that returning an absolute path is breaking for many datasets that do things like
```python
for path, f in files:
    if path.startswith(data_dir):
        ...
```
so I think I will have to add a parameter to `iter_archive` like `extract_locally=True` to avoid the breaking change, does that sound good to you ?

This makes me also think that in streaming mode it could also return a local path too, if we think that writing and deleting temporary files on-the-fly while iterating over the streaming dataset is ok.

@lhoestq I think it is a good idea to rollback to extracting the archives locally in non-streaming mode, as far as (as you mentioned) we do not store the bytes in the Arrow file for those cases to avoid "doubling" the disk space usage.

On the other hand, I don't like:
- neither the possibility to avoid extracting locally in non-streaming: the behavior should be consistent; thus we always extract in non-streaming
  - which could be the criterium to decide whether an archive should or should not be extracted? Just because I want to make a condition on path.startswith?
- nor the option to download/delete temporary files in streaming (see discussion here: https://github.com/huggingface/datasets/pull/3689#issuecomment-1032858345)

Unfortunately, in order to fix the datasets that are breaking after the rollback, I would suggest fixing their scripts so that the paths are handled more robustly (considering that they can be absolute or relative).

I agree with Albert, fixing all of the audio datasets isn't too big of a deal (yet). I can help with those if needed :)

Ok cool ! I'm completely rolling it back then

Alright I did the rollback and now you can get local paths :)
Feel free to try it out and let me know if it's good for you

I'll fix the CI tomorrow x)

Ok according to the CI there around 60+ datasets to fix

> fixing all of the audio datasets isn't too big of a deal (yet). I can help with those if needed :)

I can help with them too :)


Here is the full list to keep track of things:

- [x] air_dialogue
- [x] id_nergrit_corpus
- [ ] id_newspapers_2018
- [x] imdb
- [ ] indic_glue
- [ ] inquisitive_qg
- [x] klue
- [x] lama
- [x] lex_glue
- [ ] lm1b
- [x] amazon_polarity
- [ ] mac_morpho
- [ ] math_dataset
- [ ] md_gender_bias
- [ ] mdd
- [ ] assin
- [ ] atomic
- [ ] babi_qa
- [ ] mlqa
- [ ] mocha
- [ ] blended_skill_talk
- [ ] capes
- [ ] cbt
- [ ] newsgroup
- [ ] cifar10
- [ ] cifar100
- [ ] norec
- [ ] ohsumed
- [ ] code_x_glue_cc_clone_detection_poj104
- [x] openslr
- [ ] orange_sum
- [ ] paws
- [ ] paws-x
- [ ] cppe-5
- [ ] polyglot_ner
- [ ] dbrd
- [ ] empathetic_dialogues
- [ ] eraser_multi_rc
- [ ] flores
- [ ] flue
- [ ] food101
- [ ] py_ast
- [ ] qasc
- [ ] qasper
- [ ] race
- [ ] reuters21578
- [ ] ropes
- [ ] rotten_tomatoes
- [x] vivos
- [ ] wi_locness
- [ ] wiki_movies
- [ ] wikiann
- [ ] wmt20_mlqe_task1
- [ ] wmt20_mlqe_task2
- [ ] wmt20_mlqe_task3
- [ ] scicite
- [ ] xsum
- [ ] scielo
- [ ] scifact
- [ ] setimes
- [ ] social_bias_frames
- [ ] sogou_news
- [x] speech_commands
- [ ] ted_hrlr
- [ ] ted_multi
- [ ] tlc
- [ ] turku_ner_corpus



I'll do my best to fix as many as possible tomorrow :)

the audio datasets are fixed if I didn't forget anything :)

btw what are we gonna do with the community ones that would be broken after the fix?

Closing in favor of https://github.com/huggingface/datasets/pull/3736