Add eval and test for the example run_ner_no_trainer.py
### Feature request

Hi, thanks for the great work. I just go through the example "transformers/examples/pytorch/token-classification/", I found that run_ner.py has eval and test. However, for run_ner_no_trainer.py, there is no eval or test. I just wonder if it is possible to add these components?

### Motivation

Enhance the example code

### Your contribution

I can help to test the code.
Evaluation is done at every epoch in this script, not sure what more you need. The `no_trainer` scripts are more barebone on purpose, to make it easy for users to customize them.<|||||>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.<|||||>Evaluating NER performance with subword tokenization is complicated. It would be very instructive if you could include code that outputs one prediction for each token in the original corpus.  This would have to address the behavior of tokenizers, such as splitting words with hyphens and not prepending them with ##, etc. 

 As I understand it, the script currently performs evaluation on the subword tokens and not the restored versions.