Android: Auto installation of missing necessary SDK packages

Task-number: QTCREATORBUG-18978
Change-Id: Iac3e2c956ac3da717c6509f28b8d810827947ea0
Reviewed-by: BogDan Vatra <bogdan@kdab.com>

src/plugins/android/androidsdkmanagerwidget.h

@@ -57,6 +57,7 @@ public:
     ~AndroidSdkManagerWidget();
 
     void setSdkManagerControlsEnabled(bool enable);
+    void installEssentials();
 
 signals:
     void updatingSdk();