feat(convo): add new fields to conversation api

[sicoyle]

Description

Go SDK client updates for conversation API new fields for response format, prompt cache, usage metrics, and model return on conversation api. I added some tests too since we had none.

dapr/dapr#9241
Similar to Python SDK updates here dapr/python-sdk#902

Issue reference

Please reference the issue this PR will close: #[issue number]

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[codecov]

Codecov Report

❌ Patch coverage is 0% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.86%. Comparing base (1112e61) to head (f60327a).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
client/conversation.go	0.00%	23 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #801      +/-   ##
==========================================
+ Coverage   50.43%   54.86%   +4.43%     
==========================================
  Files          51       51              
  Lines        3438     3452      +14     
==========================================
+ Hits         1734     1894     +160     
+ Misses       1575     1419     -156     
- Partials      129      139      +10     

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[sicoyle]

The codecov patch build failure can be ignored. I added tests where there were none previously, so coverage is starting from 0%.