Android: Change default Android Asset Packaging Tool from aapt to aapt2
Android: Change default Android Asset Packaging Tool from aapt to aapt2

aapt2 was introduced in Build Tools since 26.0.2 and replaced aapt in
gradle since version 3.0.0.
Since Android.sdk now requires Build Tool version 24.0.3 it is possible
to default to aapt2.

Change-Id: Ia6ec88267ca58413592d6eadde73422311f34d74
Reviewed-by: Ivan Komissarov <96f14e4d07227e958f51f7d2898113639e9498d9@gmail.com>

qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs