chore: import upstream snapshot with attribution

dotnet/samples/GettingStartedWithProcesses/Step03/Steps/ExternalStep.cs

@@ -0,0 +1,20 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Microsoft.SemanticKernel;
+
+namespace Step03.Steps;
+
+/// <summary>
+/// Step used in the Processes Samples:
+/// - Step_03_FoodPreparation.cs
+/// </summary>
+public class ExternalStep(string externalEventName) : KernelProcessStep
+{
+    private readonly string _externalEventName = externalEventName;
+
+    [KernelFunction]
+    public async Task EmitExternalEventAsync(KernelProcessStepContext context, object data)
+    {
+        await context.EmitEventAsync(new() { Id = this._externalEventName, Data = data, Visibility = KernelProcessEventVisibility.Public });
+    }
+}