QUICK_TEST_MAIN_WITH_SETUP setup object should expose the current qml file being tested

QUICK_TEST_MAIN_WITH_SETUP allows one to provide a C++ class with methods that get called by the test. The `qmlEngineAvailable` method is called once for every test ran. Unfortunately, which test file is going to be ran is not exposed. That would be very useful information, in my case it would allow me to setup some mocking data differently. 

The simplest way to expose it would be, I think, either adding another method that will be called before `qmlEngineAvailable` with the test case, or adding an overload called on `qmlEngineAvailable` that includes the test case path as an additional argument. 

I currently need to rely on the actual implementation to track which file is being tested, which is of course not great as that's very much an implementation detail.