Add RequestThreadProc context to ETW events

[vitek-karas]

Summary

• add request context payload to RequestThreadProcStart/RequestThreadProcStop
• emit project and request identifiers from RequestBuilder
• add a unit test covering the enriched start/stop event payloads

Testing

• .\build.cmd -v quiet
• artifacts\bin\Microsoft.Build.Engine.UnitTests\Debug\net10.0\Microsoft.Build.Engine.UnitTests.exe --filter-method "RequestThreadProcEventsIncludeRequestContext"
• artifacts\bin\Microsoft.Build.Engine.UnitTests\Debug\net472\Microsoft.Build.Engine.UnitTests.exe --filter-method "RequestThreadProcEventsIncludeRequestContext"

[Copilot]

Pull request overview

This PR enriches MSBuild’s ETW RequestThreadProcStart / RequestThreadProcStop events with request context (project path + request/config identifiers) so traces can be correlated back to the originating build request. It also adds a unit test validating the new event payload shape.

Changes:

• Extend MSBuildEventSource RequestThreadProcStart/Stop (EventIds 37/38) to include request context payloads (versioned to Version = 1).
• Emit the enriched ETW events from RequestBuilder.RequestThreadProc.
• Add a unit test asserting the new ETW payload names and values.

Reviewed changes

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

File	Description
src/Framework/MSBuildEventSource.cs	Adds v1 ETW payloads to RequestThreadProc start/stop events.
src/Build/BackEnd/Components/RequestBuilder/RequestBuilder.cs	Populates and emits request context fields into the ETW start/stop events.
src/Build.UnitTests/BackEnd/RequestBuilder_Tests.cs	Adds a unit test validating the enriched start/stop ETW payload.

[AR-May]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[AlesProkop]

@AR-May Should we merge this?