Add copy of Gemini ToolConfig in local

[kumaranvpl]

Why are these changes needed?

Related issue number

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• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/docs/contributor-guide/documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[marklysze]

Thanks @kumaranvpl!

[codecov]

Codecov Report

Attention: Patch coverage is 52.11268% with 34 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
autogen/oai/gemini_types.py	50.72%	34 Missing ⚠️

Files with missing lines	Coverage Δ
autogen/oai/gemini.py	15.56% <100.00%> (+0.18%)	⬆️
autogen/oai/gemini_types.py	50.72% <50.72%> (ø)

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