Added option to modify config parameter used by Tesseract in LayoutLMV2/LayoutXLM Processor
# What does this PR do?

Giving user option to set config parameter used by Tesseract when performing feature extraction. Eg. to change psm levels while performing transcription by passing in '--psm 10' to config parameter while invoking image_to_data

It is shown that changing the psm values greatly influences the end result of LayoutLMV2/XLM, and the specific psm value is different depending on the document formatting. Refer : [PSM](https://github.com/tesseract-ocr/tesseract/issues/434)

```python
pytesseract.image_to_data(image, lang=lang, output_type="dict", config="--psm 10") 
``` 

Users can now set the tesseract config parameter during Processor initialization, like so:
```python
processor = LayoutLMv2Processor.from_pretrained("microsoft/layoutlmv2-base-uncased", ocr_lang="eng", tesseract_config="--psm 5")
```


## Before submitting
- [❌] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [✔️] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [❌] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [✔️] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [❌] Did you write any new necessary tests?


Feel free to modify as needed.
Thanks

@NielsRogge @LysandreJik 


_The documentation is not available anymore as the PR was closed or merged._<|||||>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.<|||||>Hi,

Sorry for the late reply. I'll review now.<|||||>LayoutLMv2FeatureExtractor constructor must be modified to accept tesseract_config instead of tess_config for this change. Hang on, I'll work on it.<|||||>Tried to rebase and merge with upstream but it is now changing too many files. I've created a fresh new PR here https://github.com/huggingface/transformers/pull/17733
