ProjectExplorer: Introduce IDeviceFactory::iconForId()

This adds the possibility to have an icon for a device type. Now,
a Kit can have a proper icon if just the device type but not device
is selected.

Change-Id: I2a382ffd5b46cbbf74cdd0b934b3d450d300bfff
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
Reviewed-by: Vikas Pachdha <vikas.pachdha@qt.io>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/android/androiddevice.cpp

@@ -45,10 +45,6 @@ AndroidDevice::AndroidDevice()
 {
     setDisplayName(QCoreApplication::translate("Android::Internal::AndroidDevice", "Run on Android"));
     setDeviceState(DeviceReadyToUse);
-    setDeviceIcon({Utils::Icon({{":/android/images/androiddevicesmall.png",
-                                 Utils::Theme::PanelTextColorDark}}, Utils::Icon::Tint),
-                   Utils::Icon({{":/android/images/androiddevice.png",
-                                 Utils::Theme::IconsBaseColor}})});
 }
 
 AndroidDevice::AndroidDevice(const AndroidDevice &other)