Support OTLP Protocol

[binary111]

Summary

Support the OTLP (OpenTelemetry Protocol) to publish metrics, spans, and traces from Harvest wherever possible. This will make the go-agent flexible for clients to use across various observability backends.

Desired Behavior

I should be able to use the go-agent with other backend systems like Prometheus, Datadog, etc.

Possible Solution

Based on the configuration, events are published using the OTLP protocol.

Reference: https://github.com/open-telemetry/opentelemetry-proto-go

Additional Context

I am currently not using the go-agent due to vendor lock-in. I would like to leverage New Relic's features while maintaining flexibility and avoiding vendor lock-in.