Just connect to the GUdevClient "uevent" signal and deals with
"add"/"remove" commands. This drives the installation/removal of
GSource to listen to the device.
Let's use the sysfs path of the device to make sure we only load evdev
device, not legacy mousedev ones for instance. We rely on the sysfs
API/ABI guarantees and look for devices finishing by /input%d/event%d.
This backend is a event backend that can be enabled for EGL (for now).
It uses udev (gudev) to query input devices on a linux system, listens to
keyboard events from input devices and xkbcommon to translate raw key
codes into key keysyms.
This commit only supports key events, more to follow.