Add CMake option to run androiddeployqt in aux mode

There is no option to run androiddeployqt with --aux-mode arg for cmake targets that invoke it.

Add an option like

QT_ANDROID_DEPLOY_AUXMODE

to add the --aux-mode flag to extra_args, in qt6_android_add_apk_target cmake function. 

Why?

Build the android-build directory, resolve and copy plugins, prepare other resources like libs.xml, but not running the gradle build steps. The exact reason to have --aux-mode flag, but when invoking it by cmake target but not direct execution of adqt.