Add build time measurement to Startup tool

[kotlarmilos]

Description

This PR adds support for measuring total build time in the Startup tool using binlog files.

Changes

• Add DownloadBuildArtifacts task to retrieve binlog files from the build machines
• Update run_performance_job.py to copy binlog files into the helix payload directory
• Update Startup tool to invoke BuildTimeParser
• Implement BuildTimeParser to retrieve overall publish duration, plus ILLink and Mono-specific task times

Validation

Run the internal dotnet-runtime-perf tool to verify that BuildTimeParser collects build times.

Out-of-scope

These measurements are collected from the build machines. With lack of any build time measurements atm, we want to standup these now and iterate later if needed. As suggested in dotnet/runtime#113073, apps build may be moved to Helix in the future.

Contributes to dotnet/runtime#113073

[matouskozak]

Thanks a lot for introducing these. As a follow-up we should extend this to .NET sample app scenarios.

Is there an internal CI run where we can check the output of this measurements?

[kotlarmilos]

Is there an internal CI run where we can check the output of this measurements?

Yes, invoked the internal CI. Sharing it offline.

[matouskozak]

LGTM! thank you.

[ivanpovazan]

Nice work! I only left few minor comments, thank you!