Merge pull request #3785 from windows-toolkit/sampleAppMediaFix

SampleApp fix. BitmapFileFormat moved assemblies.

Author: michael-hawker

Microsoft.Toolkit.Uwp.SampleApp/Models/Sample.cs

@@ -649,6 +649,7 @@ private static Type LookForTypeByName(string typeName)
                 GridSplitter.GridResizeDirection.Auto.GetType(), // Microsoft.Toolkit.Uwp.UI.Controls.Layout
                 typeof(MarkdownTextBlock), // Microsoft.Toolkit.Uwp.UI.Controls.Markdown
                 BitmapFileFormat.Bmp.GetType(), // Microsoft.Toolkit.Uwp.UI.Controls.Media
+                typeof(AlphaMode), // Microsoft.Toolkit.Uwp.UI.Media
                 StretchChild.Last.GetType() // Microsoft.Toolkit.Uwp.UI.Controls.Primitivs
             };