The JNI utilities (i.e. QJniObject, QJniEnvironment) are already under
qtbase as public APIs.

Permission handling is now under QCoreApplication::{check,request}Permission
and QPermission namespace.

Some of the QtAndroid namespace functions are now under QNativeInterface's
QAndroidApplication, this includes:
* sdkVersion()
* hideSplashScreen()
* context() and isActivityContext()
* runOnAndroidMainThread()

The remaining APIs are now moved as private APIs under qtbase
ee05af296f65e240f64db6470cdddafbddbf2fa3. That is until we add
new cross-platform APIs to replace their functionalities like
Intents handling, starting activites and working with Services.

Task-number: QTBUG-83251
Task-number: QTBUG-84382
Pick-to: 6.2
Change-Id: Id077f8cbbe223a987916f737fad6088fb58e470d
Reviewed-by: Ville Voutilainen <ville.voutilainen@qt.io>