Previously, trackballs were detected based on the presence of the
substring "trackball" in the device name. This had the downside of
missing devices, such as the Kensington Expert Mouse, which don't have
"trackball" in their names.
Rather than depending on the device name, use the ID_INPUT_TRACKBALL
property from udev to determine whether or not to treat a device as a
trackball.
This adds a new function, `is_trackball_device`, to MetaInputEvents, and
eliminates the `meta_input_device_is_trackball` function.
Fixes: https://gitlab.gnome.org/GNOME/mutter/issues/258
8685de9607