Consider splitting out OpenTelemetry

Problem/Motivation

I'm just getting started with OpenTelemetry but was wondering why you have Tracer API → but then group prometheus metrics and opentelemetry tracing into submodules in this project?

Wouldn't it make sense to have an OpenTelemetry project that implements the Tracer API completely separate from prometheus?

The fact that this project's composer.json requires both PHP libraries shows unnecessary coupling in my opinion.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes