Add option for distributed traces in test proxy

[scbedd]

After discussion with @heaths , I am adding an item to enable distributed tracing in test-proxy. We should take the opportunity to utilize structured logging for these messages as well.

When flag --distributed-trace is passed, the proxy should generate trace messages in stdout that other applications can consume.

This will probably require a refactor of logging in general in the proxy to get all these outputs figured out

[heaths]

This will probably require a refactor of logging in general in the proxy to get all these outputs figured out

Not necessarily. We could optionally trace from the existing ILogger messages and if you wanted to keep tracing compatible, perhaps those would log a specific trace field that could be used for identification e.g., log = "existing messages, new lines and all". I could start with that and it wouldn't prevent future growth possibilities.