Make space for and add macOS unit testing stub project

Signed-off-by: Simon Rozman <simon@rozman.si>

mac/UnitTests/main.cpp

@@ -0,0 +1,7 @@
+#include <iostream>
+
+int main(int argc, const char * argv[]) {
+	// insert code here...
+	std::cout << "Hello, World!\n";
+	return 0;
+}