Align task tags in dataset metadata
I removed all the invalid task_ids in datasts without namespace, based on the <s>(internal)</s> types.ts (Types.ts is not internal it's public) I have opened PRs to fix the task_ids in all datasets within a namespace as well.

Working on task_categories... For future reference: this fix had some complications

When trying to open a PR to fix the task tags, an exception was thrown if:
- the metadata contained "languages" or "licenses" (instead of "language" or "license")
- the metadata contained a non-valid language: `en-US` (instead of `en`), `no` (instead of `'no'`),...
- the metadata contained a non-valid license
- either `task_categories` or `task_ids` was not an array (a dict for each config)
- the metadata contained non-valid tag names

Errors:
```
ValueError: - Error: "languages" is deprecated. Use "language" instead.
```
```
ValueError: - Error: "licenses" is deprecated. Use "license" instead.
```
```
ValueError: - Error: "language[17]" must only contain lowercase characters
```
```
ValueError: - Error: "language[0]" with value "cz, de, it" is not valid. It must be an ISO 639-1, 639-2 or 639-3 code (two/three letters), or a special value like "code", "multilingual". If you want to use BCP-47 identifiers, you can specify them in language_bcp47.
```
```
ValueError: - Error: "task_ids" must be an array
``` All Hub datasets are done. great job! did you have feedback from Hub users/i.E. repo authors? Yes, @julien-c. These are some of the feedbacks:
- Most people just thank for the fix: [cahya/librivox-indonesia](https://huggingface.co/datasets/cahya/librivox-indonesia/discussions/1#6357cd8a292a050ebd705f84), [TurkuNLP/xlsum-fi](https://huggingface.co/datasets/TurkuNLP/xlsum-fi/discussions/1#6357828aa1f8ad1c31bcbe46), [coastalcph/fairlex](https://huggingface.co/datasets/coastalcph/fairlex/discussions/4#6351a527a8e595171ab1aef2)
- Why are we changing their task names? [joelito/lextreme](https://huggingface.co/datasets/joelito/lextreme/discussions/1#6351b576fe367c0d9b12041b)
  - I take note of this for the next bulk operation; besides the PR title, we should also add a description to explain the reason for the change and also maybe putting a link to some pertinent GH Issue page
- Some of them ask where to find the list of the supported task values is: [dennlinger/klexikon](https://huggingface.co/datasets/dennlinger/klexikon/discussions/3#6356b3ea80f8cb3ab777ac5c), [lmqg/qg_jaquad](https://huggingface.co/datasets/lmqg/qg_jaquad/discussions/1#635262467e4cc3135fd09f58)
  - Currently, the list is here: https://github.com/huggingface/hub-docs/blob/main/js/src/lib/interfaces/Types.ts#L85
  - Maybe we could made them more easily accessible
- Some people do not agree about current "hierarchy":
  - text-scoring: [emrecan/nli_tr_for_simcse](https://huggingface.co/datasets/emrecan/nli_tr_for_simcse/discussions/1#6357c1b128792d8cdd51e9f9) (but referring to [emrecan/nli_tr_for_simcse](https://huggingface.co/datasets/emrecan/nli_tr_for_simcse/discussions/2/files))
    - Before "text-scoring" was a task_category, with task_ids ["semantic-similarity-scoring", "sentiment-scoring"]
    - Now all three are task_ids ["text-scoring", "semantic-similarity-scoring", "sentiment-scoring"] under the task_category "text-classification"
    - People complain that their scoring tasks are not classification task
  - binary-classification: why don't we have binary-classification? We have multi-class-classification, multi-label-classification and sentiment-classification, but not binary-classification
  - symbolic-regression: [yoshitomo-matsubara/srsd-feynman_hard](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_hard/discussions/2#63614194c12a09b8a31457cc), [yoshitomo-matsubara/srsd-feynman_medium](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_medium/discussions/2#6361418aeee0d27f04379e43), [yoshitomo-matsubara/srsd-feynman_easy](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_easy/discussions/2#6361416e00905b1ffb8d0112)
    - Why don't we have symbolic-regression task?

NOTE: I'm editing this comment to add more feedback As someone with feedback on the updates (which I highly appreciate seeing included here :D), a few comments from a "user perspective":  

* I think the general confusion for me was also surrounding the hierarchy; it doesn't really become super clear (even when using the tagger space) that one is a subset of the other, especially since it seems to be still possible to include fine-grained tasks without the "parent category"?
* The datasets explorer still shows tags that are no longer valid (e.g., super specific ones such as `summarization-other-paper-abstract-generation`, but also ones that should be `task_categories`, such as `summarization`). I'm assuming this will be fixed soon, but until then it can confuse people who don't understand why they suddenly can't use seemingly still valid tags anymore.
* As I mentioned to @albertvillanova, having a dedicated page in the docs with explanations (especially wrt the difference between `task_categories` and `task_ids`) would be super helpful. However, I think it would have been sufficient to just include some description in the dataset PRs where you can link to the Github/other discussion on the topic :) That way, I can check myself what changes are expected to happen.

Thanks again for the streamlining process, I personally learned a fair bit about the tagging structure in the meantime!
Best,
Dennis Thanks to you both for your feedback! super useful! cc'ing @osanseviero too 🙂

> The datasets explorer still shows tags that are no longer valid

wait which explorer is that? is it https://huggingface.co/datasets/viewer/ ?
 Sorry, this one: https://huggingface.co/datasets  
And then selecting the "Fine-Grained Tasks". good feedback! we'll improve this Super useful feedback, thanks a lot! - Some people do not agree about current "hierarchy":
  - symbolic-regression: [yoshitomo-matsubara/srsd-feynman_hard](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_hard/discussions/2#63614194c12a09b8a31457cc), [yoshitomo-matsubara/srsd-feynman_medium](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_medium/discussions/2#6361418aeee0d27f04379e43), [yoshitomo-matsubara/srsd-feynman_easy](https://huggingface.co/datasets/yoshitomo-matsubara/srsd-feynman_easy/discussions/2#6361416e00905b1ffb8d0112)
    - Why don't we have symbolic-regression task? @albertvillanova 
Thank you for sharing our voice here!

Yes, we want `symbolic-regression` to be listed as a task. This task has been attracting attention from the machine learning/deep learning community, and unfortunately existing symbolic regression datasets are de-centralized in the community (hosted at individual platforms like author website, github, etc).
It would be great for the community if Hugging Face can support the task.
## Describe
Once we have agreed on a common naming for task tags for all open source projects, we should align on them.

## Steps
- [x] Align task tags in canonical datasets
  - [x] task_categories: 4 datasets
  - [x] task_ids (by @lhoestq)
- [x] Open PRs in community datasets
  - [x] task_categories: 451 datasets
  - [x] task_ids: 556 datasets

