fix document extractor node incorrectly processing doc and ppt files

[AugNSo]

Summary

Fixes #12889

1. In the current code, document extractor node was using python-docx library to handle doc files, which it cannot process. this commit is trying to use unstructured API to handle doc files.
2. In the current code, document extractor node is using partititon_ppt to handle ppt files, probably a leftover when unstructured[ppt] was still in pyproject.toml. This commit is trying to use unstructured API to handle ppt files.

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[crazywoola]

Please fix the lint errors.

[AugNSo]

** Run Pytest / API Tests (3.12) (pull_request) ** Cancelled after 2m

Hi, I believe the error was not caused by linting but failure to pass test for _extract_text_from_doc function, the unit test is trying to call the function to process docx files, which should be calling _extract_text_from_docx instead with my new code.

I can try merge these two functions together under _extract_text_from_doc but I don't really think it is a good idea……

EDIT: updated the unit test