rest to grpc transcoding time metric

[kevin-shelaga]

Gloo Edge Product

Enterprise

Gloo Edge Version

1.16.x

Is your feature request related to a problem? Please describe.

On top of proxy latency, a customer who heavily uses rest to grpc transcoding would like to see a metric showing just how long the transcoding is taking so they can compare it against their pure rest endpoints.

Describe the solution you'd like

rest to grpc transcoding time metric

Describe alternatives you've considered

proxy latency, but its not verbose enough

Additional Context

No response