chore: import upstream snapshot with attribution

dotnet/samples/Demos/StepwisePlannerMigration/Plugins/TimePlugin.cs

@@ -0,0 +1,21 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+#pragma warning disable IDE0005 // Using directive is unnecessary
+
+using System;
+using System.ComponentModel;
+using Microsoft.SemanticKernel;
+
+#pragma warning restore IDE0005 // Using directive is unnecessary
+
+namespace StepwisePlannerMigration.Plugins;
+
+/// <summary>
+/// Sample plugin which provides time information.
+/// </summary>
+public sealed class TimePlugin
+{
+    [KernelFunction]
+    [Description("Retrieves the current time in UTC")]
+    public string GetCurrentUtcTime() => DateTime.UtcNow.ToString("R");
+}