Add explicit QTEST macros for tests that use QCoreApplication or QApplication

The QTEST_MAIN() macro generates a main() function using QCoreApplication or QApplication, depending on whether or not QT_GUI_LIB is defined.

However, it would be nice if there were explicit QTEST macros for tests that use either QCoreApplication or QApplication, similar to how there is a QTEST_APPLESS_MAIN() macro for tests that do not use Q(Core)Application at all.