OpenTelemetry Instrumentation for Google GenAI

This OpenTelemetry instrumentation provides automatic tracing and metrics for applications using Google's Generative AI client library (`google-generativeai`). It captures details like model calls, prompts, and responses, aligning with OpenTelemetry's GenAI semantic conventions. As part of the `opentelemetry-python-contrib` project, it is currently in beta (`0.7b0`) and subject to rapid development and potential API changes.