protocol: added surface input focus
protocol: added surface input focus

on platforms, that do not use touch or (mouse-)pointer input,
inputs events are not directly related to the screen content
(e.g. surface positions and sizes).
the controller has to set the input focus for surfaces, so
they will receive input events from sources like buttons or keyboard.

Signed-off-by: Timo Lotterbach <f20969c182a2dceb7b04342e73072205394c8a83@bmw-carit.de>

ntanibata/wayland-ivi-extension,ntanibata/wayland-ivi-extension