Added qml rewarded video + java file update

[karpinochkin]

`int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);

QmlAdMobBanner::DeclareQML(); // <== Call it before loading qml
QmlAdMobInterstitial::DeclareQML(); // <== Call it before loading qml
qmlRegisterType("QtAdMobRewardedVideo", 1, 0, "QmlRewardedVideoAd"); // <== Call it before loading qml

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

return app.exec();
`

In qml file import com.dreamdev.QtAdMobRewardedVideo for rewarded video supportimport com.dreamdev.QtAdMobRewardedVideo 1.0

`
QmlRewardedVideoAd
{
id: video_ad

unitId: "ca-app-pub-xxxxxxxxxxxxxxxx/xxxxxxxxxx"
testDeviceId: ""

onRewarded: {}
onRewardedVideoAdClosed: {}
onRewardedVideoAdFailedToLoad: {}
onRewardedVideoAdLeftApplication: {}
onRewardedVideoAdLoaded: {}
onRewardedVideoAdOpened: {}
onRewardedVideoCompleted: {}
onRewardedVideoStarted: {}

Component.onCompleted: {}

}

}
`