make FulltextSearchSuggestion partial async

[Sanket17052006]

Closes #12257

Changes :

• Makes the FulltextSearchSuggestion partial asynchronous.
• Added test_fulltext_search_suggestion_partial.py

Testing

• docker compose run --rm home pytest openlibrary/tests/fastapi/test_fulltext_search_suggestion_partial.py -v

Screenshot

N/A

Stakeholders

@RayBB

[RayBB]

Excellent work here, this is very good. I'm going to remove the test file because we don't really need that for these endpoints and put it on testing to double check it.

[RayBB]

It's working excellent and should be a big help to our performance issues. Thanks for doing this one!