Remove DebugProxy from WebAssembly Server package

[Copilot]

This PR removes the Blazor WebAssembly debugging proxy functionality from the Microsoft.AspNetCore.Components.WebAssembly.Server package as part of the work to support issue #25643.

Changes Made

Removed Files:

• WebAssemblyNetDebugProxyAppBuilderExtensions.cs - Extension methods for UseWebAssemblyDebugging()
• DebugProxyLauncher.cs - Debug proxy process launcher and management

Updated Files:

• Removed all UseWebAssemblyDebugging() calls from:
  • Project templates (BlazorWeb-CSharp templates)
  • WebAssembly dev server
  • Sample applications
  • Test assets
• Updated PublicAPI.Shipped.txt to remove the debug proxy public API
• Updated project file to remove debug proxy dependencies and MSBuild targets

Impact

The debug proxy functionality is no longer available through the WebAssembly Server package. This enables the debugging infrastructure to be moved to a separate location as planned in #25643, allowing VS Code and Visual Studio to download and use the debug proxy from an alternative location.

Applications that were using UseWebAssemblyDebugging() will need to be updated once the new debugging infrastructure is available.

Fixes #31393.

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