Adds some VM tests

New tooltip in Textbox with button control
New welcome page in Settings (shown when noting is selected)
Settings are now grouped

ModernKeePass/Pages/MainPage.xaml.cs

@@ -32,7 +32,6 @@ namespace ModernKeePass.Pages
         {
             base.OnNavigatedTo(e);
             DataContext = new MainVm(Frame, MenuFrame);
-            //if (Model.SelectedItem == null) MenuFrame.Navigate(typeof(WelcomePage));
         }
     }
 }