feat(google-ai): add function calling support for Google SDK integration

[luixaviles]

PR Checklist

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• The commit message follows our guidelines: https://voltagent.dev/docs/community/contributing/#commit-convention

Bugs / Features

• Related issue(s) linked
• Tests for the changes have been added
• Docs have been added / updated
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What is the current behavior?

• The GoogleGenAIProvider does not support function call execution.
• There is no support for configuring tools or utility functions for Google SDK integration.

What is the new behavior?

• Adds support for function call execution on the GoogleGenAIProvider.
• Enables the provider to handle and execute function calls.
• Introduces tool configuration options and utility functions to facilitate integration with the Google SDK.
• Implements support for parallel function calling, allowing multiple functions to
  be called and executed concurrently.

Notes for reviewers

Here is an screenshot of the Google Agent using tools and running on the Developer Console.

[changeset-bot]

🦋 Changeset detected

Latest commit: 66b17ad

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@voltagent/google-ai	Patch

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[omeraplak]

Thank you for the contribution! Merged 🚀