.Net: Add Async Support for ConverseStreamResponse to Avoid Thread Blocking

[shethaadit]

Motivation and Context

This change replaces the use of response.Stream.AsEnumerable() with await foreach for async streaming in the Amazon Bedrock SDK. The previous method blocked the calling thread, leading to potential thread exhaustion in high-concurrency scenarios. This update aligns with best practices for asynchronous operations in .NET.

Description

• Replaced blocking foreach with await foreach for streaming ConverseStreamResponse chunks asynchronously.
• Upgraded Amazon Bedrock runtime and core SDKs to support this functionality.

Contribution Checklist

• [Y] The code builds clean without any errors or warnings
• [Y] The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• [Y] All unit tests pass, and I have added new tests where possible
• [Y] I didn't break anyone 😄

Fixes #9519

[RogerBarret0]

@shethaadit Do we really need to rely on 4.0.0-preview package for this? Can't we keep the current GA version?

[shethaadit]

Hi @RogerBarret0, this fix just got available yesterday in latest Nuget. We would need to keep the new version to get this fix.

aws/aws-sdk-net#3542 (comment)

[shethaadit]

Hi @RogerBarret0 / @markwallace-microsoft, can we merge this as it's already approved?

[rogerbarreto]

Hi @shethaadit, seems that the solution currently does not compile, please before posting the PR ensure the solution compiles and the all UT are passing.

Thanks.