demos: Update/alter console and json output paths
demos: Update/alter console and json output paths

Json is now sent to stdout instead of a file. Html and json output are
now the only two output paths that can exist in the same instance.

Change-Id: I2d28d9b996c11535bf170e7e25b5acd8f57276e1

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools