Introduce OpenTelemetry metrics and tracing

[evg-tso]

Hi,

I see that OpenTelemetry's metrics and tracing are missing in this repo.
Since OpenTracing and OpenCensus have been merged to form the OpenTelemetry project, I wonder if we should add another Metrics/Tracer implementation for OpenTelemetry here, or somewhere in the opentelemetry-java-instrumentation project.

What do you think?
If you think it's worthwhile, I can work on adding another implementation for OTEL metrics as a first step.

[protocol7]

Such a contribution would surely be welcomed :)

[korzepadawid]

Assign it to me :)

[thiagocesarj]

OpenTelemetry metrics now available thanks to @korzepadawid ! Closing the issue