[Refactor]Port C++/CX to C++/WinRT (#34198)

## Summary of the Pull Request
Removes all C++/CX code, replacing it with C++/WinRT.

## Detailed Description of the Pull Request / Additional comments
Removes all C++/CX code.
Renames interop namespaces to be better consumed by CsWinRT.
Standardizes all projects on net8.0-windows10.0.20348.0, which is a
requirement for C++/WinRT usage.
FileLocksmithLibInterop brought to stdcpplatest and static analysis
errors were corrected.
Removed now unneeded string conversion code from
FileLocksmithLibInterop.
Changed interop KeyboardHook to use a single hook across all instances.
Required because on C++/WinRT we don't have the .NET runtime to bind a
object instance to a delegate and be able to pass it to a C function
pointer argument (still no idea why this worked correctly on C++/CX to
be honest). This change actually makes us create less low level keyboard
hooks.
Changed some code that depended on arrays since WinRT/C++ returns null
instead of an empty array through the interface.

## Validation Steps Performed
Built and tested runtime.

src/settings-ui/Settings.UI.Library/Settings.UI.Library.csproj

@@ -4,9 +4,8 @@
         Condition="exists('$(SolutionDir)src\Common.SelfContained.props')" 
         Project="$(SolutionDir)src\Common.SelfContained.props" />
     <PropertyGroup>
-        <TargetFrameworks>net8.0-windows</TargetFrameworks>
         <RuntimeIdentifiers>win-x64;win-arm64</RuntimeIdentifiers>
-        <TargetFramework>net8.0-windows</TargetFramework>
+        <TargetFramework>net8.0-windows10.0.20348.0</TargetFramework>
         <Description>PowerToys Settings UI Library</Description>
         <AssemblyName>PowerToys.Settings.UI.Lib</AssemblyName>
     </PropertyGroup>
@@ -24,6 +23,7 @@
     </ItemGroup>
 
     <ItemGroup>
+        <PackageReference Include="Microsoft.Windows.CsWinRT" />
         <PackageReference Include="System.IO.Abstractions" />
     </ItemGroup>