Add BuildRequestStarted event

[JanKrivanek]

Context

We need to distinguish restore is happening for the BuildCheck feature (namely for https://github.com/dotnet/msbuild/issues/9747) This is not currently possible until receiving BuildEvaluationFinished. Team decided that it's more future wise to add the full event with all the relevant info, rather than reusing BuildEvaluationStarted event.

What should be done

• Create new BuildEventArg - named BuildRequestStarted or BuildSubmissionStarted
• Add the followind data (they will be sourced from BuildRequestData and GraphBuildRequestData):
  • ProjectFullPath
  • TargetNames
  • Flags (note - the ClearCachesAfterBuild flag might be helpful in the future for BuildCheck dedup)
  • GlobalProps
  • SubmissionId (fro the PendBuildRequest functions)
• Send the event through logging from a location all requests go through (probably BuildManager.PendBuildRequest - for GraphBuildRequestData and BuildRequestData)
• Ensure proper de/serialization in BuildEventsArgReader/Writer
• Increment binlog version, Create Binlog viewer PR (todo: give further instructions here)

Prerequisity: Verify that all the build requests go through BuildManager.PendBuildRequest and there are no other possible execution paths of build (through CLI or API) that can avoid this function

[JanKrivanek]

The addition to the binlog might be bundled with BuildCheckTracingEventArgs de/serialization - in order to minimize formats bumps