iOS: Do not boot a simulator in Booted state

It results into a simulator window with an error

Change-Id: I47d55082bf248fc6558e995158b631d75adb8617
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/ios/simulatorcontrol.h

@@ -53,6 +53,7 @@ public:
 class SimulatorInfo : public SimulatorEntity {
 public:
     bool isBooted() const { return state.compare(QStringLiteral("Booted")) == 0; }
+    bool isShutdown() const { return state.compare(QStringLiteral("Shutdown")) == 0; }
     bool available;
     QString state;
     QString runtimeName;