Making Weave API OpenAI compatible

With weave api being open ai compatible, user can just change their API in just 2 lines, then we can onboard user that used OpenAI quickly.

const openai = new OpenAI({ 
   baseURL: 
"https://pms.chasm.net/api/prompts/execute/44", 
   apiKey: OPENAI_API_KEY,
 });``` 

Also with this feature, we can integrate with Langchain easily as well, user can just change model through API


Slack Discussion: https://chasm-talk.slack.com/archives/C05PHU191GX/p1715774841176749