Track and add custom attributes for Traces similar to Metric Hook

[askpt]

Requirements

We should implement a feature to add and track custom attributes for Traces, similar to what was done for Metric Hook in PR #512. This would help enhance trace observability and flexibility in the SDK.

• Review the implementation of custom attributes in the Metric Hook (see PR feat: Add Metric Hook Custom Attributes #512)
• Propose a similar approach for Traces
• Ensure parity in attribute handling between Traces and Metrics
• Document usage and provide examples

This issue will track progress and discussions for this enhancement.

[kylejuliandev]

Would we want a specific Builder and Options class for the Trace hook? Or could a general purpose one be used in both?

For example:

var options = TelemetryHookOptions.CreateBuilder()
    .WithCustomDimension("custom_dimension_key", "custom_dimension_value")
    .WithFlagEvaluationMetadata("boolean", s => s.GetBool("boolean"))
    .Build();

OpenFeature.Api.Instance.AddHooks(new MetricsHook(options));
OpenFeature.Api.Instance.AddHooks(new TraceEnricherHook(options));

[askpt]

For this we should have separate Options objects. In case we start to have different settings for metrics and traces, we will need to introduce potential breaking down the road.