implement + enable demos

c_os/user/PreemptiveThreadDemo.h

@@ -0,0 +1,21 @@
+#ifndef __preemptive_thread_include__
+#define __preemptive_thread_include__
+
+#include "kernel/Globals.h"
+#include "kernel/threads/Thread.h"
+#include "user/PreemptiveLoopThread.h"
+
+class PreemptiveThreadDemo : public Thread {
+private:
+    PreemptiveThreadDemo(const PreemptiveThreadDemo& copy) = delete;  // Verhindere Kopieren
+
+public:
+    PreemptiveThreadDemo() {
+        kout << "Initialized PreemptiveThreadDemo" << endl;
+    }
+
+    // Thread-Startmethode
+    void run() override;
+};
+
+#endif