[WO-1581] Enable span status and renaming

[jmorrell-cloudflare]

• Introduces a new STW event spanUpdate to mirror spanOpen and spanClose. Currently only supports updating name and status but could be expanded to other properties if there is ever a need.

type SpanStatusCode = "unset" | "ok" | "error";

interface SpanStatus {
  readonly code: SpanStatusCode;
  readonly message?: string;
}

type SpanUpdateInfo =
  | { readonly type: "name"; readonly name: string }
  | { readonly type: "status"; readonly status: SpanStatus };

interface SpanUpdate {
  readonly type: "spanUpdate";
  readonly info: SpanUpdateInfo;
}

• Extends our span model with two new methods to match OpenTelemetry:

interface TracingSpanStatus {
  code: TracingSpanStatusCode;
  message?: string;
}

span.updateName(name: string): this
span.setStatus(status: TracingSpanStatus): this

[ask-bonk]

I'm Bonk, and I've done a quick review of your PR.

Adds user-tracing span status serialization and tail-stream exposure.

1. P1: Posted a suggestion for the missing InvocationSpanState::setStatus() implementation, which currently leaves the class abstract and prevents compilation.

github run

[github-actions]

The generated output of @cloudflare/workers-types matches the snapshot in types/generated-snapshot 🎉

[codecov-commenter]

Codecov Report

❌ Patch coverage is 28.01418% with 203 lines in your changes missing coverage. Please review.
✅ Project coverage is 38.11%. Comparing base (84338b9) to head (1f6faa7).

Files with missing lines	Patch %	Lines
src/workerd/api/tracing.c++	0.00%	73 Missing ⚠️
src/workerd/io/trace.c++	49.05%	45 Missing and 9 partials ⚠️
src/workerd/io/trace-stream.c++	0.00%	39 Missing and 2 partials ⚠️
src/workerd/io/tracer.c++	0.00%	21 Missing ⚠️
src/workerd/io/trace-test.c++	72.97%	0 Missing and 10 partials ⚠️
src/workerd/server/server.c++	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7348      +/-   ##
==========================================
- Coverage   38.12%   38.11%   -0.02%     
==========================================
  Files         858      858              
  Lines      262589   262871     +282     
  Branches    24314    24383      +69     
==========================================
+ Hits       100125   100205      +80     
- Misses     148816   148995     +179     
- Partials    13648    13671      +23     

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[NuroDev]

LGTM from a types PoV

[fhanau]

Make sure to squash before merge.