feat: Add TraceEnricherHookOptions Custom Attributes

[kylejuliandev]

This PR

Adds TraceEnricherHookOptions, largely a copy of MetricHookOptions from #512, to enrich the feature_flag.evaluation span event.

Example usage:

var traceHookOptions = TraceEnricherHookOptions.CreateBuilder()
    .WithCustomDimension("key1", "value1")
    .WithFlagEvaluationMetadata("provider", s => s.GetString("provider"))
    .Build();

featureBuilder.AddHostedFeatureLifecycle()
    .AddHook(new TraceEnricherHook(traceHookOptions));

These adds tags to the event associated with the span. Below is an example with the above custom dimension and metadata callback:

Related Issues

Fixes #516

Notes

Follow-up Tasks

I kept the builder method names WithCustomDimension and WithFlagEvaluationMetadata, maybe this should be different for Traces? In the Java implementation the both hook options look very similar: TracesHookOptions.java and MetricHookOptions.java

How to test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.16%. Comparing base (8c05d1d) to head (6ba5ea6).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #526      +/-   ##
==========================================
+ Coverage   87.88%   88.16%   +0.28%     
==========================================
  Files          48       49       +1     
  Lines        1972     2020      +48     
  Branches      222      228       +6     
==========================================
+ Hits         1733     1781      +48     
  Misses        191      191              
  Partials       48       48              

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