vulkan/wsi: implement missing wsi_register_device_event
These changes implement vkRegisterDeviceEventEXT and detection of monitor hotplug. Wsi launches a thread that listens to udev events and signals the appropriate device fences when hotplug hapens.
Related tests: dEQP-VK.wsi.display_control.register_device_event
Signed-off-by: Tapani Pälli tapani.palli@intel.com