adding sample for tracing custom attributes

[M-Hietala]

adding sample for tracing custom attributes

[Copilot]

Pull Request Overview

This PR adds a new sample demonstrating how to enrich OpenTelemetry traces with custom attributes via a processor, updates the test project to pull in required tracing packages, and extends the SDK README with a "Tracing" section and sample snippets.

• Introduce Sample_Telemetry_CustomAttributes.cs showcasing a CustomAttributeProcessor and usage in both async and sync scenarios
• Update Azure.AI.Projects.Tests.csproj to reference the Console and Azure Monitor OpenTelemetry exporter packages
• Enhance README.md with a new "Tracing" section containing code snippets for adding custom attributes

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
sdk/ai/Azure.AI.Projects/tests/Samples/Telemetry/Sample_Telemetry_CustomAttributes.cs	Add sample class with custom OpenTelemetry processor and usage examples
sdk/ai/Azure.AI.Projects/tests/Azure.AI.Projects.Tests.csproj	Add <PackageReference> entries for tracing exporters
sdk/ai/Azure.AI.Projects/README.md	Insert "Tracing" section and snippets for custom attributes

Comments suppressed due to low confidence (6)

sdk/ai/Azure.AI.Projects/tests/Samples/Telemetry/Sample_Telemetry_CustomAttributes.cs:76

• This sample test only prints spans to the console—consider adding assertions to verify that the custom tags (e.g., custom.session_id) are actually applied to the Activity.

        public async Task TracingCustomAttributesExample()

sdk/ai/Azure.AI.Projects/README.md:369

• [nitpick] Consider adding a note about installing the required NuGet packages (e.g., OpenTelemetry.Exporter.Console) before using these samples so users know which dependencies to add.

You can enhance telemetry data by adding custom attributes to activities through implementing a custom processor. This allows you to enrich trace data with application-specific context.

sdk/ai/Azure.AI.Projects/tests/Samples/Telemetry/Sample_Telemetry_CustomAttributes.cs:7

• [nitpick] This namespace isn't used in the sample; consider removing the using directive to keep imports clean.

using System.Collections.Generic;

sdk/ai/Azure.AI.Projects/tests/Samples/Telemetry/Sample_Telemetry_CustomAttributes.cs:9

• [nitpick] LINQ isn't used in this file; you can remove this using to reduce unnecessary dependencies.

using System.Linq;

sdk/ai/Azure.AI.Projects/tests/Samples/Telemetry/Sample_Telemetry_CustomAttributes.cs:10

• [nitpick] The System.Threading namespace isn't referenced; consider removing it to simplify imports.

using System.Threading;

sdk/ai/Azure.AI.Projects/tests/Azure.AI.Projects.Tests.csproj:19

• [nitpick] This package reference isn’t used in the sample (only console exporter is invoked). If you don’t intend to use the Azure Monitor exporter here, you can remove this line.

    <PackageReference Include="Azure.Monitor.OpenTelemetry.Exporter" />