chore: import upstream snapshot with attribution

dotnet/samples/Concepts/Resources/Plugins/StaticTextPlugin.cs

@@ -0,0 +1,19 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.ComponentModel;
+using Microsoft.SemanticKernel;
+
+namespace Plugins;
+
+public sealed class StaticTextPlugin
+{
+    [KernelFunction, Description("Change all string chars to uppercase")]
+    public static string Uppercase([Description("Text to uppercase")] string input) =>
+        input.ToUpperInvariant();
+
+    [KernelFunction, Description("Append the day variable")]
+    public static string AppendDay(
+        [Description("Text to append to")] string input,
+        [Description("Value of the day to append")] string day) =>
+        input + day;
+}