Add support for reporting metrics in completion response headers in o…

[coolkp]

FIX #10086

Implement

• reporting of metrics in completion response headers in orca format
• reporting of metrics in orca proto format in Orca metrics proto #10475

[github-actions]

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @coolkp.

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[coolkp]

dropping in favor of #12854. only in header no overhead for default case