This module provides a Tracer Provider and a Context Manager for use with OpenTelemetry on Fastly Compute.
FastlyTracerProvider is a basic TracerProvider implementation based on
BasicTracerProvider, but uses FastlyStackContextManager (described below)
as its default Context Manager implementation.
FastlyStackContextManager relies on the fact that
Compute applications only ever have a single FetchEvent, as entirely new
containers are spun up for every request. Thus, it's safe to globally set the
current "fetch event span" context and allow the context manager to fall back to
that when an event is active.