Feature: Allow easy 3rd party library tracing of statesman gem

[theaxel]

We utilize tracing heavily for our application observability via Datadog.

There is currently no easy way to hook into the state machine lifecycle to generate spans for a trace.
We added this feature via ActiveSupport ::Notifications which is used in many other gems for that same purpose.

Currently it is a monkey patch in our code and would like to integrate it directly into the gem.

Does that align with your vision?

[stephenbinns]

This does sound interesting! it's certainly an approach we've taken before with other Gems - I'm sure we'd be happy to review a PR if you opened one