Spring-ai Initial Observability for Models in Spring AI

• Observation APIs for chat, embedding and image models
• Conventions based on OpenTelemetry Semantic Conventions for GenAI
• Instrumentation for OpenAI chat, embedding, and image models
• Autoconfiguration for observability for OpenAI

See proposal and design in gh-953.

Comment From: ThomasVitale

@codefromthecrypt thanks a lot for reviewing the pull request, much appreciated. This will be a step 1 towards a larger observability arrangement. There's a few things right now that need to be synced with the SemConv, mostly those that are currently under discussions (like how to shape the prompt and completion content) and some metrics, but we'll get there.

I'm currently working on some documentation, including an overview of the status of the GenAI SemConv adoption in Spring AI, for better tracking the process. I'm planning to publish that in the upcoming days. I'll ping you on that PR once I submit it, it would be great to get your feedback on it. Thank you!

OpenLit and OpenLLMetry are great projects, I'm also following their adoption journey of the semantic conventions.