WO-1582 Add span.recordException

[jmorrell-cloudflare]

We currently send uncaught exceptions to the tail worker, but this would allow us to capture them on the span where they were emitted

This adds span.recordException

 recordException(
    exception:
      | string
      | {
          code: string | number;
          name?: string;
          message?: string;
          stack?: string;
        }
      | {
          code?: string | number;
          name: string;
          message?: string;
          stack?: string;
        }
      | {
          code?: string | number;
          name?: string;
          message: string;
          stack?: string;
        },
  ): void;

The types here should match OpenTelemetry JS's span.recordException, though we don't yet support passing in your own timestamp:

https://github.com/open-telemetry/opentelemetry-js/blob/main/api/src/trace/span.ts#L144-L150
https://github.com/open-telemetry/opentelemetry-js/blob/main/api/src/common/Exception.ts#L6-L38

The STW interface already supports an exception event. This adds code?: string | number to the payload.

[ask-bonk]

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

Adds Span.recordException() and serializes exception codes to tail streams.

1. [P1] Posted 1 inline finding.

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 26.34146% with 151 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.65%. Comparing base (1162ae2) to head (219c797).

Files with missing lines	Patch %	Lines
src/workerd/api/tracing.c++	0.00%	74 Missing ⚠️
src/workerd/io/tracer.c++	39.62%	31 Missing and 1 partial ⚠️
src/workerd/io/trace.c++	50.00%	14 Missing and 8 partials ⚠️
src/workerd/io/trace-stream.c++	0.00%	9 Missing and 1 partial ⚠️
src/workerd/server/server.c++	0.00%	9 Missing ⚠️
src/workerd/io/trace-test.c++	73.33%	0 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7081      +/-   ##
==========================================
- Coverage   67.72%   67.65%   -0.08%     
==========================================
  Files         458      458              
  Lines      129441   129631     +190     
  Branches    21167    21223      +56     
==========================================
+ Hits        87661    87697      +36     
- Misses      28927    29069     +142     
- Partials    12853    12865      +12     

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