[FEATURE REQUEST] Allow callers to specify an optional `trace_id` on HTTP JSON API calls and thread it through to the Ledger API server

[stefanobaghino-da]

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I confirm that, if this is a feature request that has security implications, I already contacted [email protected] and followed the responsible disclosure policy.

I confirm that this is not a question or a request for technical support by the community, for which the Daml forum is available.

What is the problem you want to solve?

Tracking requests going through the HTTP JSON API all the way into the Ledger API.

What is the solution you would propose?

The Ledger API allows to add a trace identifier to calls going in via gRPC calls metadata. One could provide such identifier via the HTTP JSON API to track the full life cycle of a call originating from there. Ideally the identifier could possibly be also threaded through all the way from the Ledger API as those calls are served.

Describe alternatives you've considered

None, really. Not sure whether there are any.