Create `FormatEvent` implementation that would make it easier to log trace and span IDs.

[mladedav]

Feature Request

Motivation

tracing does not provide a way to customize fields that are printed in its formaters (issue). People often want trace ID and span ID to be printed in their logs so that it is easier to correlate with thraces.

The solution most people (me included) arrive at is copying and tweaking Json from tracing so that it prints what they want.

Proposal

Instead of everyone forking that implementation, it could live here. It's not the best solution and I look forward to tracing having a way to natively extend the format, but until then I think it would be better to provide this here.

Alternatives

• Do nothing
• Solve the issue in tracing