Auto-ping CODEOWNERS on Codeflow PR test failures

[ellahathaway]

When a Codeflow PR for the SDK has failing tests, we currently rely on build duty to manually identify the relevant test owner and notify them. Add automation so that on test failure, the system determines the failing test’s path and checks whether that path is covered by an owner entry in the repo’s CODEOWNERS file. If an owner is found, have AI automatically post a PR comment pinging the owner(s) with a brief summary and link to the failing test output, so ownership routing happens immediately without requiring human intervention.

[ellahathaway]

@premun - IIRC darc subscriptions had an approximation of this feature back when codeflow came from specific repos (ie failures in the dotnet/Roslyn PR would ping the Roslyn team). That doesn't work anymore with flow coming from dotnet/dotnet. Is there any plan to re-implement or fix this for VMR codeflows?

[premun]

@ellahathaway do you mean the PR Notification Tags on the subscription field is not respected anymore when there's a build failure?

There hasn't been any other mechanism.

[premun]

This field is currently not set for any backflow subscriptions to SDK: https://maestro.dot.net/subscriptions?search=%3Abf%20%2Fsdk&showDisabled=False