Improve unit testing directory structure

Separate Qt tests and gtest tests
Add a basic shadow of the project structure
Add a few simple tests to demonstrate usage

tests/src/Gui/Assistant.cpp

@@ -0,0 +1,7 @@
+#include "gtest/gtest.h"
+
+#include "Gui/Assistant.h"
+
+TEST(Assistant, first){
+
+}