Add headphone volume to output report for DS4 v2 controllers

[Ryochan7]

As noted in an issue for the Jays2Kings version, the DS4 version 2 controller exposes the headphone jack directly to Windows when plugged into a PC via USB. I just bought a DS4 v2 for testing. Currently, DS4Windows will set the headphone volume to 0. The workaround that is used for the Sony dongle would allow headphone support to work. However, DS4Windows might have to know which version of the controller is being used in order to know if the volume level should be monitored. Setting the headphone volume level in the output packet for a version 1 controller connected via USB would probably be fine but that would require extra processing for something that the version 1 controller cannot support.

Jays2Kings#17

[Ryochan7]

Although the approach used is not very flexible, headphone volume support now works for DS4 v2 controllers connected via USB. For now, the VID and PID of a device is checked and only the currently known combination for the DS4 v2 is matched. Later on, an array or some other data structure might have to be used to let the application know which devices have support for the headphone jack on Windows.