Fix exception tracing for streaming responses in invocations protocol

[singankit]

When an invoke handler returns a StreamingResponse, exceptions thrown during body iteration (e.g. in async generators) were not being recorded on the OTel trace span. This wraps the streaming body iterator to catch exceptions, log them with the invocation ID, and record them on the current span so they appear correctly in App Insights traces.

Description

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[Copilot]

Pull request overview

This PR addresses observability gaps for invocation handlers that return StreamingResponse: exceptions raised during streaming body iteration are now caught, logged with the invocation ID, and recorded on the active OpenTelemetry span so they show up in traces (e.g., Application Insights).

Changes:

• Add a wrapper around StreamingResponse.body_iterator to catch iteration-time exceptions and record them on the current OTel span.
• Extend imports to support streaming and async-iterator typing.