CmdPal: collection of Run Commands nits (#42092)

* Path items were being treated inconsistently
* We shouldn't re-enumerate a directory on every keystroke
* A bunch of elements had empty TextToSuggest (which makes it crazier
  that it ever worked right)


Vaguely regressed in #41956
related to #39091

src/modules/cmdpal/Microsoft.CmdPal.UI/App.xaml.cs

@@ -160,7 +160,7 @@ public partial class App : Application
 
         services.AddSingleton<IRootPageService, PowerToysRootPageService>();
         services.AddSingleton<IAppHostService, PowerToysAppHostService>();
-        services.AddSingleton(new TelemetryForwarder());
+        services.AddSingleton<ITelemetryService, TelemetryForwarder>();
 
         // ViewModels
         services.AddSingleton<ShellViewModel>();