feat: add inital in memory dispatcher

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

src/request.tests/_fixtures/ScalarTestWrapperHandler.cs

@@ -0,0 +1,12 @@
+// Copyright (c) The Geekeey Authors
+// SPDX-License-Identifier: EUPL-1.2
+
+namespace Geekeey.Request.Tests;
+
+public class ScalarTestWrapperHandler<T> : IScalarRequestHandler<ScalarTestWrapperRequest<T>, string>
+{
+	public Task<string> HandleAsync(ScalarTestWrapperRequest<T> request, CancellationToken cancellationToken)
+	{
+		return Task.FromResult($"Handled-{request.Item}");
+	}
+}