atspi: handle "gesture_required" attribute

atspi: handle "gesture_required" attribute

The elementary sends the "detail2" information highlight based on the attribute
"gesture_required" when an object grabs.

If an object has attribute key "gesture_required", and "scroll" for its value,
then the "detail2" is 1. Otherwise, the "detail2" is 0.

The screen-reader AT client calls "ObjectNeedsScrollGesture" method of
e-mod-tizen-screen-reader window manager module with object geometry value,
if the "detail2" is 1. Otherwise, the object geometry value is not used.

The e-mod-tizen-screen-reader window manager module will send mouse event
based on the object geometry.

Application side could use this feature setting attribute as below:
 - elm_atspi_accessible_attribute_append(btn, "gesture_required", "scroll");

This patch set depends on:
https://review.tizen.org/gerrit/#/c/142108/ (screen-reader)
https://review.tizen.org/gerrit/#/c/142107/ (e-mod-tizen-screen-reader)

Change-Id: I0b731ce947be569b2d782fdc21f18c79ffebf70e