shreyanid c2853e4ac3
refactor languages parameter for pdf partition functions (#1334)
### Summary

In order to support language functionality other than Tesseract OCR, we
want to represent languages provided for either partitioning accuracy or
OCR as a standard list of langcodes as strings.

### Details

Adds `languages` (a list of strings) as a parameter to pdf partitioning
functions. Marks `ocr_languages` for deprecation. Adds a new file
`lang.py` for language-related helper functions.

Coming up: langcode standardization, language detection

### Test

Call `partition_pdf` or `partition_pdf_or_image` with a variety of
strategies, languages, or `ocr_languages`.
- inclusion of `ocr_languages` as a parameter should display a
deprecation warning
- the other valid call outputs should be no different from the current
outputs.

ex:
```
from unstructured.partition.pdf import partition_pdf

elements = partition_pdf(filename="example-docs/DA-1p.pdf", strategy="hi_res", languages=["eng", "spa"])
print("\n\n".join([str(el) for el in elements]))
```
2023-09-12 16:15:26 +00:00
..