Android: save the service under QtNative with QtNative.setService()

Otheriwse Qt C++ code will not be able to find it.

Task-number: QTBUG-115016
Pick-to: 6.7
Change-Id: Id3a2efb1f33cb60a523359e1ad646a394e24397e
Reviewed-by: Petri Virkkunen <petri.virkkunen@qt.io>
Reviewed-by: Janne Juntunen <janne.juntunen@qt.io>
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

src/android/jar/src/org/qtproject/qt/android/QtServiceBase.java

@@ -23,6 +23,8 @@ public class QtServiceBase extends Service {
             return;
         }
 
+        QtNative.setService(this);
+
         QtServiceLoader loader = new QtServiceLoader(this);
         loader.loadQtLibraries();
         QtNative.startApplication(loader.getApplicationParameters(), loader.getMainLibrary());