Add ControllerTest Overlay and support not loading new state if previous loaded

examples/PoolBox/application/src/Overlay/ControllerTest/controller_test.cpp

@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+namespace ControllerTest {
+    void main() {
+        printf("CONT: BlubbBlubbBlubb!!\n");
+    }
+}

examples/PoolBox/application/src/Overlay/GPUTest/gpu_test.cpp

@@ -2,7 +2,6 @@
 
 namespace GPUTest {
     void main() {
-        printf("BlubbBlubbBlubb!!\n");
-        while(true);
+        printf("GPU: BlubbBlubbBlubb!!\n");
     }
 }

examples/PoolBox/application/src/Overlay/Overlays.hpp

@@ -1,4 +1,9 @@
 #pragma once
+
+namespace ControllerTest {
+    void main();
+}
+
 namespace GPUTest {
     void main();
 }