Remove legacy LightModalViewTabControl

Author: jcansdale

src/GitHub.UI/Assets/Controls.xaml

@@ -9,7 +9,6 @@
         <ResourceDictionary Source="Controls/RoundedCheckBox.xaml" />
         <ResourceDictionary Source="Controls/FilterTextBox.xaml" />
         <ResourceDictionary Source="Controls/GitHubLinkButton.xaml" />
-        <ResourceDictionary Source="Controls/LightModalViewTabControl.xaml" />
         <ResourceDictionary Source="Controls/ScrollViewerWithShadow.xaml" />
         <ResourceDictionary Source="../Controls/Octicons/OcticonImage.xaml" />
     </ResourceDictionary.MergedDictionaries>