Add error metrics tracking for workflow incidents

[sfmskywalker]

This commit introduces a new ErrorMetrics class to track and record workflow errors, leveraging OpenTelemetry. It replaces DefaultErrorSpanHandler with DefaultExceptionHandler and adds support for custom metric handling through the IErrorMetricHandler interface. Additionally, the middleware and service configuration have been updated to integrate error metrics tracking seamlessly.

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This change is 

[Copilot]

Pull Request Overview

This PR introduces error metrics tracking into workflow incident handling by replacing the old error span handler with a new exception handler and adding support for custom error metric handlers using OpenTelemetry. Key changes include:

• Adding the new ErrorMetrics class and IErrorMetricHandler interface for tracking workflow errors.
• Updating middleware and DI registrations to integrate error metric tracking.
• Renaming and consolidating error span handlers to align with the new behavior.

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/modules/Elsa.OpenTelemetry/Models/ErrorMetricContext.cs	Introduces a new context model for error metrics using a modern constructor syntax.
src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs	Updates the middleware constructor and tag assignments, and integrates error tracking.
src/modules/Elsa.OpenTelemetry/Metrics/ErrorMetrics.cs	Implements the error metrics tracking mechanism with OpenTelemetry counters.
src/modules/Elsa.OpenTelemetry/Handlers/FaultExceptionHandler.cs	Renames and extends the fault exception handler to process error metric contexts.
src/modules/Elsa.OpenTelemetry/Handlers/DefaultExceptionHandler.cs	Introduces a unified exception handler covering span and metric contexts.
src/modules/Elsa.OpenTelemetry/Features/OpenTelemetryFeature.cs	Updates DI registrations to incorporate the new error metric tracking components.
src/modules/Elsa.OpenTelemetry/Contracts/IErrorMetricHandler.cs	Adds an interface to support customizable error metric handling.
src/apps/Elsa.Server.Web/Program.cs	Adjusts metrics configuration to register the new error metrics and updates exporter settings.

Comments suppressed due to low confidence (2)

src/modules/Elsa.OpenTelemetry/Middleware/OpenTelemetryTracingActivityExecutionMiddleware.cs:33

• Ensure that using activity.Id instead of activity.NodeId for the 'activity.id' tag is consistent with the identifier usage elsewhere in the system.

span.SetTag("activity.id", activity.Id);

src/apps/Elsa.Server.Web/Program.cs:157

• [nitpick] Verify that the instrumentation lines commented out are intentionally disabled; if so, consider adding a comment to clarify their purpose or remove them if no longer necessary.

.AddMeter(ErrorMetrics.MeterName)

[Copilot]

[nitpick] Include a brief comment explaining the purpose of the ErrorMetrics registration to aid future maintainability.

Suggested change

	.AddScoped<IErrorMetricHandler, FaultExceptionHandler>()
	.AddScoped<IErrorMetricHandler, FaultExceptionHandler>()
	// Registers the ErrorMetrics service to track and report error-related metrics for OpenTelemetry.