Add option to report as a gamepad (rather than a joystick)

[fasteddy516]

Currently, the USB HID descriptor reports a JoystickXL device as a "joystick", but some applications only appear to recognize devices that report as a "gamepad".

If all that is required to extend support to these applications is to report as a "gamepad", than I see no reason to not provide an option (probably in joystick_xl.hid.create_joystick() to do just that. It is possible that there are other limiting factors (i.e. input quantity restrictions, vastly different descriptor structure, etc.) that will make it impractical to implement, but it is worth investigating.