feat: add inital in memory dispatcher

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

src/request.tests/_fixtures/DerivedScalarRequest.cs

@@ -0,0 +1,9 @@
+// Copyright (c) The Geekeey Authors
+// SPDX-License-Identifier: EUPL-1.2
+
+namespace Geekeey.Request.Tests;
+
+public class DerivedScalarRequest : IScalarRequest<string>
+{
+	public int Value { get; set; }
+}