Propogating OpenTelemetry via IDocumentListener

[STRUDSO]

Trying to add some opentelemetry to an examplar application we have internally.
Thought i might share the code here with you guys, to get your view on it.

Pull request is here:
#3667

In my project i use Verify to assert my trace. I just printed it to output here, because i think it provides a good visualization of the spans and so.

Let me know anything you would like me to rework or if i should throw the code somewhere else, maybe it belongs more in the sample area.

[jeremydmiller]

If you want to put this into the samples, that's fine. I'm not yet really seeing anything though that our existing built in Otel exporting doesn't cover yet.