Upgrade C# projects to .NET 10

[gewarren]

Contributes to #12713.

[Copilot]

Pull request overview

This PR advances #12713 by modernizing a set of C# snippet projects—primarily converting legacy .NET Framework project files to SDK-style projects targeting .NET 10, and updating a few WCF-related snippets to be runnable/compilable in modern .NET.

Changes:

• Upgrade several snippet .csproj files to SDK-style and retarget to net10.0 / net10.0-windows.
• Modernize parts of the WCF snippets (CoreWCF-based hosting for faultcontractattribute, and programmatic client/channel setup in some samples).
• Remove legacy .NET Framework-era ancillary content (for example, the XBAP readme) and minor code cleanups (unused using, accessibility changes).

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
snippets/csharp/VS_Snippets_CFX/faultcontractattribute/cs/Host/services.cs	Switch to CoreWCF types and adjust the fault contract/service implementation.
snippets/csharp/VS_Snippets_CFX/faultcontractattribute/cs/Host/hostapplication.cs	Replace ServiceHost hosting with ASP.NET Core + CoreWCF hosting.
snippets/csharp/VS_Snippets_CFX/faultcontractattribute/cs/Host/host.csproj	Convert host project to SDK-style Web project targeting net10.0 with CoreWCF packages.
snippets/csharp/VS_Snippets_CFX/faultcontractattribute/cs/Client/client.csproj	Convert client project to SDK-style targeting net10.0 and add WCF client packages.
snippets/csharp/VS_Snippets_CFX/channelfactorybehaviors/cs/proxycode.cs	Remove config-based proxy constructors to better align with modern usage patterns.
snippets/csharp/VS_Snippets_CFX/channelfactorybehaviors/cs/iendpointbehaviormessageinspector.cs	Refactor endpoint behavior/message inspector implementation for modern .NET.
snippets/csharp/VS_Snippets_CFX/channelfactorybehaviors/cs/client.csproj	Convert client project to SDK-style targeting net10.0 and add required packages.
snippets/csharp/VS_Snippets_CFX/channelfactorybehaviors/cs/client.cs	Change client to create binding/address programmatically rather than relying on config.
snippets/csharp/VS_Snippets_CFX/callbackbehaviorattribute/cs/client.csproj	Convert client project to SDK-style targeting net10.0 and add WCF client packages.
snippets/csharp/VS_Snippets_CFX/callbackbehaviorattribute/cs/client.cs	Update duplex client creation to be more “modern .NET”-friendly (programmatic setup).
snippets/csharp/System.Windows/TextAlignment/Overview/FlowDocumentSnippets.csproj	Convert WPF snippet project to SDK-style and retarget to net10.0-windows.
snippets/csharp/System.Windows.Documents/Hyperlink/NavigateUri/Readme.txt	Remove legacy XBAP/.NET Framework 3.0 readme content.
snippets/csharp/System.Windows.Automation/AutomationEventArgs/.ctor/ElementProvider.csproj	Convert WinForms snippet project to SDK-style net10.0-windows.
snippets/csharp/System.Windows.Automation/AndCondition/.ctor/CustomElementClient.csproj	Convert Windows desktop client snippet project to SDK-style net10.0-windows.
snippets/csharp/System.Windows.Automation/AndCondition/.ctor/ClientForm.cs	Minor cleanup (remove unused using).

Suppressed comments (1)

snippets/csharp/VS_Snippets_CFX/channelfactorybehaviors/cs/iendpointbehaviormessageinspector.cs:16

• This type is referenced as a config-based behavior extension in hostapplication.exe.config (<behaviorExtensions><add ... type="Microsoft.WCF.Documentation.EndpointBehaviorMessageInspector, HostApplication" />). Removing BehaviorExtensionElement and the BehaviorType/CreateBehavior overrides means the <endpointMessageInspector /> element can no longer be instantiated from config, and ApplyDispatchBehavior is now a no-op so the service-side inspector won’t be applied.

  class EndpointBehaviorMessageInspector : IEndpointBehavior, IClientMessageInspector
  {
    //<snippet4>
    // IEndpointBehavior Members
    public void AddBindingParameters(ServiceEndpoint serviceEndpoint, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)