GraphQL: Report multiple query errors

[marcotc]

Captures GraphQL error information as span events:

This is necessary because each query can have multiple errors (GraphQL spec for the "errors" field), which cannot reported using span tags (span tags only support one error per span).

Change log entry
GraphQL query errors are now reported as Span Events. This includes support for multiple errors, if present.

How to test the change?
All changes have unit tests and system-tests: DataDog/system-tests#3840

[datadog-datadog-prod-us1]

Datadog Report

Branch report: graphql-error-event
Commit report: a5b863e
Test service: dd-trace-rb

✅ 0 Failed, 22066 Passed, 1476 Skipped, 5m 30.76s Total Time

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.36066% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.71%. Comparing base (3e81a5a) to head (a5b863e).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...cing/contrib/graphql/support/application_schema.rb	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4177      +/-   ##
==========================================
- Coverage   97.71%   97.71%   -0.01%     
==========================================
  Files        1358     1358              
  Lines       82501    82549      +48     
  Branches     4223     4226       +3     
==========================================
+ Hits        80618    80659      +41     
- Misses       1883     1890       +7     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-18 01:14:53

Comparing candidate commit a5b863e in PR branch graphql-error-event with baseline commit 3e81a5a in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.

[github-actions]

👋 Hey @marcotc, please fill "Change log entry" section in the pull request description.

If changes need to be present in CHANGELOG.md you can state it this way

**Change log entry**

Yes. A brief summary to be placed into the CHANGELOG.md

(possible answers Yes/Yep/Yeah)

Or you can opt out like that

**Change log entry**

None.

(possible answers No/Nope/None)

^{Visited at: 2025-01-18 00:02:08 UTC}

[marcotc]

Reminder: remove this before merging.
Leaving this here during code review because it proves that this PR passes system-test changes.