IDevice: Replace QSharedPointer with std::shared_ptr

According to https://wiki.qt.io/Things_To_Look_Out_For_In_Reviews
QSharedPointer impl is poor and it's going to be removed from Qt 7.

Replace QWeakPointer with std::weak_ptr.
Replace QEnableSharedFromThis with std::enable_shared_from_this.
Use std::static_pointer_cast and std::dynamic_pointer_cast
for casts used with QSharedPointer before.

Change-Id: If255a100c790860934f36d52906b93f33c31cfe8
Reviewed-by: hjk <hjk@qt.io>

src/plugins/ios/iosconfigurations.cpp

@@ -403,7 +403,7 @@ void IosConfigurations::updateSimulators()
     DeviceManager *devManager = DeviceManager::instance();
     Id devId = Constants::IOS_SIMULATOR_DEVICE_ID;
     IDevice::ConstPtr dev = devManager->find(devId);
-    if (dev.isNull()) {
+    if (!dev) {
         dev = IDevice::ConstPtr(new IosSimulator(devId));
         devManager->addDevice(dev);
     }