Add LLM monitoring support for JavaScript

[AbhiPrasad]

Problem Statement

Add support for https://docs.sentry.io/product/insights/llm-monitoring/ in JavaScript

Solution Brainstorm

Things we can support:

• @vercel/ai: https://github.com/vercel/ai
• Amazon Bedrock: https://github.com/aws/aws-sdk-js-v3/tree/main/clients/client-bedrock
• Anthropic SDK: https://github.com/anthropics/anthropic-sdk-typescript
• Azure OpenAI SDK: https://github.com/Azure/azure-sdk-for-js/tree/main/sdk/openai/openai
• Cohere AI: https://www.npmjs.com/package/cohere-ai
• Google Vertex: https://github.com/googleapis/google-cloud-node
• Google Generative AI: https://www.npmjs.com/package/@google-ai/generativelanguage
• HuggingFace JS: https://github.com/huggingface/huggingface.js/
• Mistral JS: https://github.com/mistralai/client-js
• OpenAI JS: https://github.com/openai/openai-node
• Langchain JS: https://github.com/langchain-ai/langgraphjs

[colin-sentry]

Currently difficult because we need to annotate the LLM spans with the pipeline span's name, and there is no nice way to pass context down in a runtime agnostic way

In python this is done with ContextVar

Maybe we can convert the pipeline span into a transaction, and pull down its name into the children that way?

[AbhiPrasad]

In python this is done with ContextVar

In Node.js we can use AsyncLocalStorage, which is what the SDK uses to maintain parent-child relationship between spans even with async behaviour.

In fact the Sentry scope lives on-top of async local storage in the Node SDK, so you can just store stuff on the scope to use.