hid2hci: rewrite (and break) rules and device handling

hid2hci: rewrite (and break) rules and device handling

We must never access random devices in /dev which do not belong to
the event we are handling. Hard-coding /dev/hidrawX, and looping over all
devices is absolutely not acceptable --> hook into hidraw events.

We can not relay on (rather random) properties merged into the parent
device by earlier rules --> use libudev to find the sibling device
with a matching interface.

Libusb does not fit into udev's use case. We never want want to scan
and open() all usb devices in the system, just to find the device
we are already handling the event for --> put all the stupid scanning
into a single function and prepare for a fixed libusb or drop it later.