fix: Updated ThreadMessage struct with latest fields based on OpenAI docs

[ecoralic]

Describe the change
ThreadMessage has deprecated fields, and new fields are missing, so requests with files cannot be made.

Provide OpenAI documentation link
https://platform.openai.com/docs/api-reference/threads/createThread

Describe your solution
Updated ThreadMessage based on OpenAI docs.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.88%. Comparing base (774fc9d) to head (460bd13).
Report is 27 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #792      +/-   ##
==========================================
+ Coverage   98.46%   98.88%   +0.42%     
==========================================
  Files          24       26       +2     
  Lines        1364     1343      -21     
==========================================
- Hits         1343     1328      -15     
+ Misses         15        9       -6     
  Partials        6        6              

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[MontiMarco92]

Hi @ecoralic. Thanks for this. I think that FileIDs should still remain for backwards compatibility with V1, what do you think? Besides, now Content can be a string or an array of objects. Check this related issue

[sashabaranov]

Thank you!

[beastmaximus]

What about MessageRequest struct? Should it also contain Attachments field just like ThreadMessage does?