Common voice validated partition
Hi @patrickvonplaten - could you please advise whether this would be a welcomed change, and if so, who I consult regarding the unit-tests? I'd be happy with adding this change. @anton-l @lhoestq - what do you think? Cool ! I just fixed the tests by adding a dummy `validated.tsv` file in the dummy data archive of common_voice

I wonder if you should separate the train/valid/test configuration from the validated/invalidated configuration of the splits ? 
In particular having `validated` along with the train/valid/test splits could be a bit weird since it comprises them. We can do that if you think it makes more sense. Otherwise it's also good as it is right now :)
 Thanks! I think that there are 2 cases for using the validated partition: 1) trainset = {validated - dev - test}, dev and test as they come; 2) train, dev, and test sampled from validated manually with the desired ratios.
In either case, I think that it's quite a big change on the HF interface part, so could as well be taken care of in the client code. Or is it not? (In which case, what's the most compact way to implement this?) What's important IMO is to let the users as much flexibility as they need - so we try to not do too much regarding splits to not constrain users. So I guess the way it is right now is ok. Can you confirm that it's ok @patrickvonplaten and that it won't break some speech training script out there ? @lhoestq all split names are explicit in our example scripts, so this shouldn't break anything, feel free to merge :)
I'll go ahead and add this to the official `mozilla-foundation` datasets as well  Good for me! This has no real down-sides IMO and surely won't break any training scripts.
This patch adds access to the 'validated' partitions of CommonVoice datasets (provided by the dataset creators but not available in the HuggingFace interface yet).
As 'validated' contains significantly more data than 'train' (although it contains both test and validation, so one needs to be careful there), it can be useful to train better models where no strict comparison with the previous work is intended.