RED metrics for numaflow apis

[mshakira]

Summary

need basic RED metrics (requests, errors and latency) for numaflow apis

Use Cases

When would you use this? when numaflow UI is served in production environment, admin should be able to monitor the health status of apis.

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Message from the maintainers:

If you wish to see this enhancement implemented please add a 👍 reaction to this issue! We often sort issues this way to know what to prioritize.

[vigith]

This will be a tricky one to alert on since the metrics are based on usage.

[whynowy]

We should expose those metrics anyways.