ux: set Focusable by XAML instead of hard coded

Author: love-linger

src/Views/ChangeCollectionView.axaml.cs

@@ -96,7 +96,6 @@ public event EventHandler<RoutedEventArgs> ChangeDoubleTapped
 
         public ChangeCollectionView()
         {
-            Focusable = true;
             InitializeComponent();
         }
 

src/Views/WorkingCopy.axaml

@@ -65,6 +65,7 @@
       <!-- Unstaged Changes -->
       <v:ChangeCollectionView Grid.Row="1"
                               x:Name="UnstagedChangesView"
+                              Focusable="True"
                               IsUnstagedChange="True"
                               SelectionMode="Multiple"
                               Background="{DynamicResource Brush.Contents}"
@@ -100,6 +101,7 @@
       <!-- Staged Changes -->
       <v:ChangeCollectionView Grid.Row="3"
                               x:Name="StagedChangesView"
+                              Focusable="True"
                               SelectionMode="Multiple"
                               Background="{DynamicResource Brush.Contents}"
                               ViewMode="{Binding Source={x:Static vm:Preference.Instance}, Path=StagedChangeViewMode}"