First Pass Lab Migration with Lab.API 2.x (#3710)

[cpp11nullptr]

• Add comprehensive certificate reload logic tests and lab migration updates

• Add certificate test fixes to lab migration

• Fixed certificate validation logic in MockHttpMessageHandler to use thumbprint-based comparison instead of object reference equality
• Added robust certificate store verification with timing controls to handle asynchronous store operations
• Implemented unique certificate naming with GUID prefixes to prevent cross-framework test interference
• Resolved AADSTS700027 authentication errors and parallel test execution conflicts

Combined with lab migration changes for comprehensive update.

• Fix lab API migration compilation errors

• Fix missing System.Diagnostics using statement in CertificatesObserverTests.cs
• Update UserConfig.UPN to userConfig.Upn in integration and performance tests
• Fix string interpolation syntax errors in authority URL construction

These changes resolve compilation failures caused by:

1. Missing using statement for Stopwatch class
2. Lab API migration UserConfig property name changes (UPN → Upn)
3. Escaped quotes in string interpolation causing syntax errors

• Complete lab API migration fixes for WebAppUiTests

• Fix UserConfig.UPN to userConfig.Upn in TestingWebAppLocally.cs
• Fix LabUserHelper to LabResponseHelper in TestingWebAppLocally.cs and WebAppCallsApiCallsGraphLocally.cs
• Fix LabResponse type and GetB2CLocalAccountAsync method in B2CWebAppCallsWebApiLocally.cs

All WebAppUiTests compilation errors from lab API migration are now resolved.

• Remove unused labResponse variable in B2C test

The B2C test uses Azure Key Vault credentials, not lab infrastructure, so the LabResponseHelper.GetUserConfigAsync call was unused.

• Fix authentication configuration and clean up test constants

• Updated TestConstants.cs to correct vault references and remove unused constants
• Configured IntegrationTestService for certificate-based authentication
• Fixed Key Vault references to use msidlabs vault with LabAuth certificate
• Removed unused OBOClientKeyVaultUri and BuildAutomationKeyVaultName constants
• Ensured all test constants are aligned with id4slab1 tenant

• Update lab tenant app configs

• Fix UI test stability and update test config

• Use ID4s Key Vault for integration test secret

• Update Microsoft.Identity.Lab.Api to 2.0.0

• Remove conflict markers

• Restore ID4s Key Vault constants

• Fix JSON indentation in appsettings.json files

• blazorserver-calls-api/Client: Fix ClientId and Scopes indentation
• MultipleAuthSchemes: Fix ClientId indentation
• aspnet-mvc/OwinWebApi: Fix ClientId indentation
• E2E Tests/IntegrationTestService: Fix Domain indentation in AzureAd and AzureAd2