[PTRun]Fix search being abandoned while cycling results (#27409)

* [Launcher] ignoring key preses while previous key press processing is ongoing

* extending TextChangedEventArgs with Initiator, storing and using initiator for the event lifetime to avoid overwriting of the initiator when parallel events occur.

* extending code with check on event object presence

src/modules/launcher/PowerLauncher/TextChangedEventWithInitiatorArgs.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace PowerLauncher
+{
+    internal sealed class TextChangedEventWithInitiatorArgs : TextChangedEventArgs
+    {
+        public TextChangedEventWithInitiatorArgs(RoutedEvent id, UndoAction action)
+            : base(id, action)
+        {
+        }
+
+        public bool IsTextSetProgrammatically { get; set; }
+    }
+}