Add agent monitoring support for `google-genai`

[AbhiPrasad]

Problem Statement

Similar to what we do for anthropic and openai add support for https://github.com/googleapis/python-genai.

(PyPI: https://pypi.org/project/google-genai/)

Solution Brainstorm

The instrumentation should match what we need for agents monitoring.

If you would like to see this get supported, please leave a react on the issue and a comment. This helps us prioritize this internally. Thanks!