Feature/nvidia nim integration

[soumilinandi]

Problem:
Currently there are no examples on how to integrate with NVIDIA NIMS

Solution:
Since NVIDIA has already built a nim connector with LiteLLM, and Google ADK directly adds LiteLLM, we showcase an example of how to use nvidia models using LiteLLM connector

Testing Plan

Please describe the tests that you ran to verify your changes. This is required
for all PRs that are not small documentation or typo fixes.

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Please include a summary of passed pytest results.

Manual End-to-End (E2E) Tests:

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

Additional context

Add any other context or screenshots about the feature request here.

[adk-bot]

Response from ADK Triaging Agent

Hello @soumilinandi, thank you for creating this PR!

To help us review your contribution more effectively, could you please address the following points from our contribution guidelines:

• Associated Issue: This PR adds a new feature example. Could you please create a GitHub issue describing this feature and link it to this PR?
• Testing Plan: Could you please update the "Manual End-to-End (E2E) Tests" section in your PR description? Please include the setup steps, the commands you ran, and the console output or screenshots showing that the example works as expected.

This information is crucial for our reviewers to understand and verify your changes. You can find more details in our CONTRIBUTING.md. Thanks!

[hangfei]

We'd love to accept this contribution. When it's ready, let us know and we can merge.

[soumilinandi]

@hangfei This PR is ready for review, thanks for taking a look before! I don't think it requires any new tests since it's just an example but let me know if anything is needed.