Add LabelsWrapper.Do() overload with state

[martincostello]

• Add new overload to LabelsWrapper to support passing through state to avoid allocating closures.
• Update the application in the integration tests to also target .NET 8 and use more modern C# features.
• Update integration tests to use Python 3.12.
• Fix some code analysis warnings.

Cherry-picked from #118.

[Copilot]

Pull Request Overview

This PR refactors the integration test application to support multi-targeting, improves code quality, and adds new tracing integrations. The changes include updating the project to target both .NET 8.0 and .NET 6.0, refactoring the application to use dependency injection, and enhancing the Pyroscope library with a new generic overload for label wrapping.

• Added support for multi-targeting .NET 8.0 and .NET 6.0
• Refactored integration test code to use modern C# patterns and dependency injection
• Extended LabelsWrapper with a generic overload to support stateful lambda callbacks

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
itest.Dockerfile	Updated sed command to match TargetFrameworks (plural) in the Dockerfile build step
Pyroscope/Pyroscope/LabelsWrapper.cs	Added generic Do<T> overload and extracted common cleanup logic to ResetLabels method
Pyroscope/Pyroscope.sln	Added three new projects to the solution (OpenTelemetry, OpenTracing, and Rideshare integration test)
Pyroscope/Pyroscope.OpenTracing/PyroscopeSpanBuilder.cs	Changed _parent field to readonly and made PyroscopeScope class private sealed
IntegrationTest/ScooterService.cs	Removed unused using System.Diagnostics, made DoSomeOtherWork static, and improved numeric literal readability
IntegrationTest/Rideshare.csproj	Changed from single target framework to multi-targeting, enabled implicit usings and latest language version
IntegrationTest/Properties/launchSettings.json	Added new launch profile for local development
IntegrationTest/Program.cs	Refactored to use modern top-level statements and dependency injection instead of static service instances
IntegrationTest/OrderService.cs	Refactored to use new generic LabelsWrapper.Do overload with static lambdas, removed unused variable
IntegrationTest/Dockerfile.load-generator	Updated Python version from 3.9 to 3.12
IntegrationTest/CarService.cs	Converted method to expression-bodied member
IntegrationTest/BikeService.cs	Converted method to expression-bodied member

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