feat:[response_format] Bedrock client structured output

[priyansh4320]

Why are these changes needed?

This pull removes the bedrock unsupported warning on structured output / response_format param and adds support for response format referanced via beedrock documentation.
https://aws.amazon.com/blogs/machine-learning/structured-data-response-with-amazon-bedrock-prompt-engineering-and-tool-use/

Related issue number

#2225

Checks

• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/latest/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.

[joggrbot]

📝 Documentation Analysis

All docs are up to date! 🎉

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✅ Latest commit analyzed: 173737f | Powered by Joggr

[codecov]

Codecov Report

❌ Patch coverage is 8.95522% with 61 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
autogen/oai/bedrock.py	8.95%	61 Missing ⚠️

Files with missing lines	Coverage Δ
autogen/oai/bedrock.py	24.12% <8.95%> (-3.50%)	⬇️

... and 19 files with indirect coverage changes

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