Simplifying Output from Text Classification Pipelines
### Feature request

> This feature request references the content discussed in a [HF thread](https://discuss.huggingface.co/t/i-have-trained-my-classifier-now-how-do-i-do-predictions/3625).

I was just wondering if there is a particular reason why the output of the `pipe` shown above is a double list?

For instance, the output of the following:

```python
from transformers import TextClassificationPipeline

model = ...
tokenizer = ...
pipe = TextClassificationPipeline(model=model, tokenizer=tokenizer, return_all_scores=True)
# outputs a list of dicts like [[{'label': 'NEGATIVE', 'score': 0.0001223755971295759},  {'label': 'POSITIVE', 'score': 0.9998776316642761}]]
res = pipe("I love this movie!")

```

is a list that has _two_ square brackets (i.e., `[[ ... ]]`). This means the indexing process to grab say the negative score requires:

```python
neg = res[0][0]["score"]
```

This could be enhanced by simply returning a single dictionary object:

```python
res = {"label":["NEGATIVE", "POSITIVE"], "score":[0.0001, 0.9998]}

```

### Motivation

This idea came from reading a [HF discussion thread](https://discuss.huggingface.co/t/i-have-trained-my-classifier-now-how-do-i-do-predictions/3625). It was two years ago, so I did not want to reopen the conversation there. 

Also, I think this is a feature addition, but feel free to correct me if I am wrong. 

### Your contribution

I do not currently have plans to submit a PR, but if there is interest from the HF team, then I will take a harder look and comment here if I can make the change and submit a PR.

My initial guess is that this is not something bothers many users. 
This is also something we cannot change without breaking the code of many many users :-)<|||||>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.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.