feat: add inital in memory dispatcher

Add a simple in memory dispatcher for scalar requests and stream request.

src/request.tests/_fixtures/ScalarWrapperBehavior.cs

@@ -0,0 +1,13 @@
+// Copyright (c) The Geekeey Authors
+// SPDX-License-Identifier: EUPL-1.2
+
+namespace Geekeey.Request.Tests;
+
+public class ScalarWrapperBehavior<T>(ScalarTestTracker tracker) : IScalarRequestBehavior<ScalarTestWrapperRequest<T>, string>
+{
+	public async Task<string> HandleAsync(ScalarTestWrapperRequest<T> request, ScalarHandlerDelegate<string> next, CancellationToken cancellationToken)
+	{
+		tracker.Executed = true;
+		return await next(request, cancellationToken);
+	}
+}