Prometheus translation modes and content negotiation

[ArthurSens]

Related to https://github.com/open-telemetry/opentelemetry-specification/issues/4494

Changes

This change focuses on three things:

• Flexibilization of underscore scaping
• Flexibilization of unit and type suffix additions
• Add content negotiation

The goal is to mimic Prometheus' existing configuration that controls the translation of metric names when receiving OTLP metrics via its /otlp endpoint. Configuration alignment will help users migrate in both directions (Prometheus/Collector) when switching their metrics collection systems.

Additional Information

Some further reading might be helpful for reviewers:

• Our guide for receiving metrics via OTLP, specifically the UTF-8 section.
• Prometheus content-negotiation for UTF-8.

---

• [X] Related issues https://github.com/open-telemetry/opentelemetry-specification/issues/4494
• [ ] Links to the prototypes (when adding or changing features)
• [ ] CHANGELOG.md file updated for non-trivial changes
• [ ] spec-compliance-matrix.md updated if necessary

[ArthurSens]

Folks, I'm out until June 25th. @ywwg is picking this up while I'm gone :)

I've removed the draft mode to help Owen with his notification settings

[github-actions[bot]]

This PR was marked stale due to lack of activity. It will be closed in 7 days.

[ywwg]

not stale

[ywwg]

(it won't let me remove the stale label)

[ArthurSens]

The CI failure seems unrelated. Could someone re-trigger it? 😇

[reyang]

@ArthurSens could you update the changelog?

[dashpole]

I think this is ready to be merged