Re-use parent console if it's available
Re-use parent console if it's available

* This means we won't get an ugly console window popping up when running
  renderdoccmd on windows, but if we run it from a terminal then we'll
  get output as normal.
* One downside is that cmd.exe seems to snoop the exe type (GUI or
  console) and if it's a GUI application it returns to the prompt
  immediately. bash for example though waits for process termination.
* The other is that pipe redirects to file don't work properly.

baldurk/renderdoc,baldurk/renderdoc,cgmb/renderdoc,baldurk/renderdoc,googlestadia/renderdoc,michaelrgb/renderdoc,TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,googlestadia/renderdoc,googlestadia/renderdoc,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,michaelrgb/renderdoc,etnlGD/renderdoc,etnlGD/renderdoc,googlestadia/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,baldurk/renderdoc,etnlGD/renderdoc,cgmb/renderdoc,michaelrgb/renderdoc,michaelrgb/renderdoc,Zorro666/renderdoc,etnlGD/renderdoc,cgmb/renderdoc,cgmb/renderdoc,cgmb/renderdoc,michaelrgb/renderdoc,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,baldurk/renderdoc,TurtleRockStudios/renderdoc_public,etnlGD/renderdoc,etnlGD/renderdoc,googlestadia/renderdoc