* Fixes registration of event handler for xinput-2 device changes,
revealed by this improvement.
* Pushes `.unwrap()` panic-ing outwards to callers.
* Includes a description of what the X11 call was doing when a failure
was encountered.
* Fixes a variety of places where the X11 reply wasn't being inspected
for failures.
* Destroys windows on failure during setup. New structure makes it
possible for the caller of `open_window` to carry on despite failures,
and so partially initialized window should be removed (though all calls
I looked at also panic currently).
Considered pushing this through `linux/x11/client.rs` too but figured
it'd be nice to minimize merge conflicts with #20853.
Release Notes:
- N/A
Michael Sloan
c9f2c2792c