Show navigate to editor hint on status bar

When a PR is checked out and the diff view gets focus, show a navigate to editor hint on status bar.

Author: jcansdale

src/GitHub.App/Services/PullRequestEditorService.cs

@@ -468,6 +468,12 @@ void EnableNavigateToEditor(ITextView textView, IPullRequestSession session, IPu
         {
             var view = vsEditorAdaptersFactory.GetViewAdapter(textView);
             EnableNavigateToEditor(view, session, file);
+
+            textView.GotAggregateFocus += (s, e) =>
+                statusBar.ShowMessage(VisualStudio.UI.Resources.NavigateToEditorStatusMessage);
+
+            textView.LostAggregateFocus += (s, e) =>
+                statusBar.ShowMessage(string.Empty);
         }
 
         void EnableNavigateToEditor(IVsTextView textView, IPullRequestSession session, IPullRequestSessionFile file)

src/GitHub.VisualStudio.UI/Resources.Designer.cs

@@ -416,4 +416,7 @@
   <data name="AddSingleComment" xml:space="preserve">
     <value>Add a single comment</value>
   </data>
+  <data name="NavigateToEditorStatusMessage" xml:space="preserve">
+    <value>Press Enter to navigate to Editor</value>
+  </data>
 </root>