Add IBM Wastonx AI Semantic Convention

[gyliu513]

Area(s)

area:gen-ai

Is your change request related to a problem? Please describe.

Besides semantic convention for gen ai, we also need semantic convention for different LLM providers, openai already have its own at https://github.com/open-telemetry/semantic-conventions/blob/main/docs/gen-ai/openai.md, this issue is trying to add watsonx ai here.

Describe the solution you'd like

Add some specific semantic convention for watsonx ai.

Describe alternatives you've considered

No response

Additional context

No response

[gyliu513]

@madhutadiparthi4ibm