add missing style registration

Author: vgromfeld

Microsoft.Toolkit.Uwp.UI.Controls.Core/Themes/Generic.xaml

@@ -7,6 +7,7 @@
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/InAppNotification/InAppNotification.xaml" />
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/Loading/Loading.xaml" />
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/Menu/Menu.xaml" />
+        <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/MetadataControl/MetadataControl.xaml" />
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/RadialProgressBar/RadialProgressBar.xaml" />
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/RotatorTile/RotatorTile.xaml" />
         <ResourceDictionary Source="ms-appx:///Microsoft.Toolkit.Uwp.UI.Controls.Core/TabbedCommandBar/TabbedCommandBar.xaml" />