OpenTelemetry integration

[sunng87]

• Data model: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/overview.md#metrics-data-model-and-sdk

[sunng87]

https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/otlp.md OTLP protocol