Add seamless support for open-telemetry in the client

[wokalski]

Here's an OCaml library for open telemetry

The details are unclear to me... i.e. how should we propagate the ids. There are also multiple propagators:

• W3C TraceContext. MAY alternatively be distributed as part of the OpenTelemetry API.
• W3C Baggage. MAY alternatively be distributed as part of the OpenTelemetry API.
• B3.
• Jaeger.

I don't understand how/if they are stitched together