Update android sources to support AndroidX, cause this is the future of android libraries. https://developer.android.com/jetpack/androidx/

For example, I want to use new https://developer.android.com/reference/androidx/biometric/BiometricPrompt in my Qt app. For it, I need QtActivity to extend FragmentActivity from androidx, not just the activity. Of course, I edit manually Qt java sources, and everything works fine, but I thing that this is good point to be added in any future qt release.