examples: add an option to force a device request for WCID descriptors

* Add option 'w' to force the use of a Device Request rather than an
  Interface Request when querying the WCID OS Extended Properties descriptor.
* This is due to a WinUSB limitation where all Interface Requests have the
  wIndex set to the interface number.
* This assumes that the WCID firmware answers both Device and Interface requests
  equally.