Feature: Tracing providers

[heitorlessa]

Ability to switch Tracing providers while keeping the same UX

[heitorlessa]

After research, all tracers have distinct initialization, nomenclature (some OpenTracing, some unique to them like X-Ray), and not all of them handle async, thread-safe operations the same way.

To support this, it'd mean bringing lots of complexity to maintain, and unknown bugs. Customers can choose not to use the Tracer middleware if they already have their own Tracer provider.

Closing as we will not implement and will instead provide X-Ray escape hatches to customers, and simplify Tracer scope