Inject k8s metadata in response headers

[clayton-gonsalves]

💸 TL;DR

Consume downward facing k8s info. enrich http response headers with above metadata for debugging.

The last commit is a potential implementation with the k8s client added to the metadatabp pkg. It would not be needed immediately but I can see it being required to fetch more fine grained data from k8s.

🧪 Testing Steps / Validation

Tested locally.

✅ Checks

• [x] CI tests (if present) are passing
• [x] Adheres to code style for repo