TokenClassificationPipeline: top-k predictions
# 🚀 Feature request

Optional argument for TokenClassificationPipeline to output top-k predictions instead of limiting output to argmax.

## Motivation

Having access to the top-k prediction distribution is useful in a number of scenarios, such as confidence calibration (https://arxiv.org/abs/1706.04599) or generating pseudo-labels (https://arxiv.org/abs/1911.04252).

## Your contribution

I'm happy to submit a PR with the proposed changes, if this contribution is deemed useful.
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/master/CONTRIBUTING.md) are likely to be ignored.