input.c: give control of default_grab_keyboard_key to a shell.

In automotive usecase, a surface which is not focused also wants to
receive keyboard event. E.g. Media Player in background wants to receive
volume up/down.

Signed-off-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA@xddp.denso.co.jp>
ivi-layout: support ivi_layout_UpdateInputEventAcceptanceOn.

This api allows us to desable or enable receiving input events per
surface. As a default, all surface can receive all events. For the time
being, the list of devices is defined as enum_ivi_input_device;
keyboard, pointer, and touch.

Keyboard: All surfaces enabled with keyboard device will receive keyboard
          event.
Pointer : TODO, not yet supported by desable/enable by this API.
Touch   : TODO, not yet supported by desable/enable by this API.
FOR DEBUG: Add logs for input focus.

Signed-off-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA@xddp.denso.co.jp>