Ported instrumentation from OpenTracing to OpenTelemetry

[jkowall]

I wanted to share that we have implemented and improved the instrumentation for the demo app. We did this mostly so that we could do better demos of the application than how opentracing works in this repo today. As many of you know OpenTracing is frozen and OpenTelemetry is where the future of instrumentation is.

We would be happy to donate it upstream. Right now this lives in our repo. https://github.com/logzio/microservices-demo

In this new repo we have added in our deployment markers, which can be replaced by other such simple APIs, and we've included a simple configuration for the proper OpenTelemetry exporter, but you can substitute it with any exporter.

Let me know if you have questions or comments.

[jkowall]

I should also mention that we added Prometheus support with remote write for the app metrics! Pointed to our service for now, but easily swapped for any other backend.