Add missing Windows XAML components to the WinUI Visual Studio configuration

Investigate and update the WinUI Visual Studio configuration to include the components required for the Windows XAML build targets.

On a clean machine, the setup can fail after running `OneTimeSetup.cmd` and applying the repository `.vsconfig` with errors indicating that the following files are missing:

- `Microsoft.Windows.UI.Xaml.Cpp.targets`
- `Microsoft.Windows.UI.Xaml.CSharp.targets`

Scope:

- Reproduce the failure on a clean machine using the current setup flow.
- Identify the Visual Studio components that provide the missing Windows XAML targets.
- Determine whether `.vsconfig`, `.vsconfig_buildtools`, or both need to be updated.
- Add the missing component IDs to the appropriate configuration files.
- Confirm that the components are available for the supported Visual Studio version.
- Validate `init` and a complete WinUI build after importing the updated configuration.
- Confirm that the fix works without manually selecting additional Visual Studio components.

Acceptance criteria:

- A clean setup no longer reports missing `Microsoft.Windows.UI.Xaml.*.targets`.
- The required components are installed through the appropriate repository configuration.
- `init` completes successfully.
- A complete WinUI build succeeds without manually modifying the Visual Studio installation.

Start with OneTimeSetup.cmd and the repository .vsconfig and .vsconfig_buildtools files, then reproduce the missing Microsoft.Windows.UI.Xaml.*.targets errors on a clean machine. Identify the Visual Studio component IDs that provide those targets and determine which configuration files require them. Done means init and a complete WinUI build succeed without manually selecting additional components.

Written by the indexing model from the issue text.