new version of Ted Talks IWSLT (WIT3)
> Nice thank you ! Actually as it is a translation dataset we should probably have one configuration = one language pair no ?
> 
> Could you use the same trick for this dataset ?

I was looking for this input, infact I had written a long post on the Slack channel,...(_but unfortunately due to the holidays didn;t get a respones_). Initially I had tried with language pairs and then with specific language configs. 

I'll have a look at the `opus-gnomes` dataset
 Oh sorry I must have missed your message then :/
I was off a few days during the holidays

Hopefully this trick can enable the use of any language pair (+ year ?) combination and also simplify a lot the dummy data creation since it will only require a few configs. Updated it as per the comments. But couldn't figure out why the dummy tests are failing >> 
```
$RUN_SLOW=1 pytest tests/test_dataset_common.py::LocalDatasetTest::test_load_real_dataset_ted_talks_iwslt
.....
....
tests/test_dataset_common.py:198: in check_load_dataset
    self.parent.assertTrue(len(dataset[split]) > 0)
E   AssertionError: False is not true
```
In the previous iteration #1608 I had used language pairs. Which created 21,582 configs (109*108) !!! 

Now, TED talks in _each language_ is a separate config. So it's more cleaner with _just 109 configs_  (one for each language). Dummy files were created manually. 

Locally  I was able to clear the `python datasets-cli test datasets/......` . Which created the `dataset_info.json`  file . The test for the dummy files was also cleared. However couldn't figure out how to specify the local data folder for the real dataset


**Note: that this requires manual download of the dataset.** 
**Note2: The high number of _Files changed (112)_ is because of the large number of dummy files/configs!**