fix: missing await on async calls and bedrock keyerror

[priyansh4320]

Why are these changes needed?

This PR is a fix on:
Bedrock: handle optional tool params without KeyError.

• standardize async detection across Agent by using is_coroutine_callable

Related issue number

#2219
#2218

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: 4511439 | Powered by Joggr

[codecov]

Codecov Report

❌ Patch coverage is 94.73684% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
autogen/agentchat/conversable_agent.py	91.66%	0 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
autogen/oai/bedrock.py	33.84% <100.00%> (+6.21%)	⬆️
autogen/agentchat/conversable_agent.py	65.12% <91.66%> (-0.91%)	⬇️

... and 18 files with indirect coverage changes

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