Add OpenTelemetry tracer

[peterdeme]

For the trace dropping, I've tried multiple things:

• custom sampler: didn't work. we dropped the parent span, but couldn't access child spans.
• don't call span.End() for dropped spans - this works but children spans still show up in the UI
• filter spans in otel-collector.yml - same issue, only drops the parent span

[ilya-hontarau]

For the trace dropping, I've tried multiple things:

I think the only thing we can do is to create an issue in the otel sdk?
https://github.com/open-telemetry/opentelemetry-go/issues

[peterdeme]

@ilya-hontarau I'll probably do but keep in mind that this is a fairly serious standard, so all SDKs would need to follow and implement it, so I don't have high hopes