Advertise pen File in Solution on Inline Comment view

Make the `Open File in Solution` command and keyboard shortcut discoverable by advertising on the inline comment view task bar.

Author: jcansdale

src/GitHub.InlineReviews/ViewModels/InlineCommentPeekViewModel.cs

@@ -75,6 +75,14 @@ public InlineCommentPeekViewModel(
                 {
                     FromLine = peekService.GetLineNumber(peekSession, triggerPoint).Item1,
                 }));
+
+            NavigateToEditor = ReactiveCommand.CreateAsyncTask(
+                Observable.Return(true),
+                async _ =>
+                {
+                    // TODO: Execute the `openFileInSolutionCommand`.
+                    await Task.Delay(1000);
+                });
         }
 
         /// <summary>
@@ -96,6 +104,11 @@ public ICommentThreadViewModel Thread
         /// </summary>
         public ReactiveCommand<Unit> PreviousComment { get; }
 
+        /// <summary>
+        /// Gets a command which navigates to the position of this comment in the live editor.
+        /// </summary>
+        public ReactiveCommand<Unit> NavigateToEditor { get; }
+
         public void Dispose()
         {
             threadSubscription?.Dispose();

src/GitHub.InlineReviews/Views/InlineCommentPeekView.xaml

@@ -96,7 +96,20 @@
                         <Rectangle Canvas.Left="9" Canvas.Top="6" Width="6" Height="1" Fill="{DynamicResource VsBrush.CommandBarOptionsGlyph}" StrokeThickness="1"/>
                     </Canvas>
                 </Button>
+                
                 <Separator Background="{DynamicResource GitHubButtonBorderBrush}" Style="{StaticResource {x:Static ToolBar.SeparatorStyleKey}}" />
+
+                <Button Margin="2 0" Padding="2" Command="{Binding NavigateToEditor}"
+                        Style="{StaticResource GitHubToolbarButton}">
+                    <Button.ToolTip>
+                        <TextBlock FontSize="11">Open Solution File at Caret (Enter)</TextBlock>
+                    </Button.ToolTip>
+
+                    <Canvas Width="16" Height="16">
+                        <!-- TODO: Double check these brushes since they don't seem like the right fill colors -->
+                        <Polygon Points="8 8 8 4 4 4 4 8 1 8 6 14 11 8" Fill="{DynamicResource VsBrush.CommandBarOptionsGlyph}" StrokeThickness="1"/>
+                    </Canvas>
+                </Button>
             </StackPanel>
         </Border>