Add support for baggage propagation

[satvu]

Issue describing the changes in this PR

resolves #11026

Worker PR: Azure/azure-functions-dotnet-worker#3319

Pull request checklist

IMPORTANT: Currently, changes must be backported to the in-proc branch to be included in Core Tools and non-Flex deployments.

• Backporting to the in-proc branch is not required
  • Otherwise: Link to backporting PR
• My changes do not require documentation changes
  • Otherwise: Documentation issue linked to PR
• My changes should not be added to the release notes for the next release
  • Otherwise: I've added my notes to release_notes.md
• My changes do not need to be backported to a previous version
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• My changes do not require diagnostic events changes
  • Otherwise: I have added/updated all related diagnostic events and their documentation (Documentation issue linked to PR)
• I have added all required tests (Unit tests, E2E tests)

[Copilot]

Pull request overview

Adds baggage propagation support to the host→language-worker gRPC invocation contract so distributed OpenTelemetry baggage can flow into worker execution context (addressing #11026).

Changes:

• Extends RpcTraceContext in the worker protobuf to include a baggage map.
• Populates the new TraceContext.Baggage on invocation requests when OpenTelemetry telemetry mode is enabled.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/WebJobs.Script.Grpc/azure-functions-language-worker-protobuf/src/proto/FunctionRpc.proto	Adds a new baggage field to RpcTraceContext for baggage propagation.
src/WebJobs.Script.Grpc/Channel/GrpcWorkerChannel.cs	Copies current baggage into the invocation request trace context when OpenTelemetry is enabled.

[liliankasem]

Changes look good, but tests should be fixed the task delay is not great and some tests require proper cleanup. Wrap setup/clear in a try/finally (or IAsyncLifetime.DisposeAsync) to keep cross-test isolation.