[Application][Tizen] Add support for using the Tizen task manager to change to Crosswalk applications

## CHERRY-PICKING these to Crosswalk-4

If we want to be able to use the Tizen task manager to alternate between Crosswalk application, we should set the `_NET_WM_PID` property of the windows that the applications created to be the PID of the process used to launch the application (`xwalk-launcher`).