Expose udev device to compositors

[YaLTeR]

The current DrmNode::ty() is wrong on FreeBSD: niri-wm/niri#3013 (comment)

However, according to @mahkoh, minor number isn't a good way to tell apart the node types even on Linux (it overflows after 128), rather we need the udev sysname, like is done here in wlroots: https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/a962d58727bf5a95ef0da50dce21031728c92f2c/backend/session/session.c#L182

But Smithay doesn't currently expose the udev device to compositors. It is accessible here (event):

smithay/src/backend/udev.rs

Line 154 in 61f5a0d

match event.event_type() {

Maybe a way to go from dev_t back to the udev device, but I'm not sure what that way is (all these DRM concepts are somewhat confusing).