If a pad device for a tablet exists, reloading the configuration,
removing/reading the device or even suspending the system will recreate
the same Wayland input device multiple times.
Make sure we don't re-create the same Wayland device more than
necessary.
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Sway has basic support for drawing tablets, but does not expose
properties such as pressure sensitivity. This implements the wlr tablet
v2 protocol, providing tablet events to Wayland clients.