Port input focus to C# sample

Author: jeffstall

Samples/Islands/DrawingIsland/DrawingCppTestApp/WinMain.cpp

@@ -5,7 +5,6 @@
 
 namespace winrt
 {
-    using namespace Microsoft::UI;
     using namespace Microsoft::UI::Composition;
     using namespace Microsoft::UI::Content;
     using namespace Microsoft::UI::Dispatching;

Samples/Islands/DrawingIsland/DrawingCsTestApp/Program.cs

@@ -1,6 +1,6 @@
-using System;
-
-using Microsoft.UI;
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
 using Microsoft.UI.Composition;
 using Microsoft.UI.Content;
 using Microsoft.UI.Dispatching;
@@ -30,6 +30,11 @@
 siteBridge.Show();
 siteBridge.Connect(drawing.Island);
 
+// Move initial focus to the island.
+var focusNavigationHost = InputFocusNavigationHost.GetForSiteBridge(siteBridge);
+focusNavigationHost.NavigateFocus(FocusNavigationRequest.Create(
+    FocusNavigationReason.Programmatic));
+
 queue.RunEventLoop();
 
 controller.ShutdownQueue();