Zipkin (and OpenTracing) tracing providers do not provide context propagation

[tjquinno]

Environment Details

• Helidon Version: 4.x
• Helidon SE or Helidon MP
• JDK version:
• OS:
• Docker version (if applicable):

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Problem Description

The Jaeger and OpenTelemetry tracing providers both provide context propagation.

But neither the OpenTracing provider nor the Zipkin provider does so.

Addressing #8846 would allow the Zipkin provider to do propagation very similarly to how our OTel provider does. That change plus this one would put Zipkin on an equal footing with OTel and Jaeger as providers.

Given that OpenTracing is essentially retired we might not choose to invest the time to add propagation for it. But Zipkin probably should do propagation.