style: Apply clang-format to all C++ files

- Format MainWindow.cpp, MainWindow.h, main.cpp
- Format test files (test_main.cpp, test_mainwindow.cpp)
- Fixes Jenkins clang-format policy check

Entire-Checkpoint: ea47c089bf3a

qt6-after/qt6-migrated-benchmark/main.cpp

@@ -1,7 +1,8 @@
-#include <QApplication>
 #include "MainWindow.h"
 
-int main(int argc, char *argv[])
+#include <QApplication>
+
+int main(int argc, char* argv[])
 {
     QApplication a(argc, argv);
     MainWindow w;