Aurum: Introduce new atspi event callback system.

Aurum: Introduce new atspi event callback system.

- usage :

1. callback function
bool deactive_cb(void *data, A11yEvent type, std::string pkg)
{
        return false;
}

AccessibleWatcher::getInstance()->registerCallback(A11yEvent::EVENT_WINDOW_DEACTIVATE, &deactive_cb, nullptr);

2. lambda expression
AccessibleWatcher::getInstance()->registerCallback(A11yEvent::EVENT_WINDOW_ACTIVATE, [](void *data, A11yEvent type, std::string pkg) { return true; }, nullptr);

Change-Id: I1401e6d71c5579967ab7094a8b84545bb3ad3c4b