Bump to WinUI 2.8.0-prerelease.220118001

Author: Sergio0694

samples/MvvmSampleUwp/MvvmSampleUwp.csproj

@@ -265,7 +265,7 @@
       <Version>7.1.2</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.UI.Xaml">
-      <Version>2.7.0</Version>
+      <Version>2.8.0-prerelease.220118001</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.Xaml.Behaviors.Uwp.Managed">
       <Version>2.0.1</Version>