visibility: Create client data for visibility by a hook, 'E_CLIENT_HOOK_NEW_CLIENT_PO...

visibility: Create client data for visibility by a hook, 'E_CLIENT_HOOK_NEW_CLIENT_POST' instead of 'E_EVENT_CLIENT_ADD'.

There is a problem that if we use 'E_EVENT_CLIENT_ADD', then we cannot fetch
a aux hint into E_Vis_Client. Becase ecore event can be happend later than fetching
aux hint which is called by dispatching wayland protocol.
Thus, we need to create a data, E_Vis_Client by 'E_CLIENT_HOOK_NEW_CLIENT_POST',
so that we can prepare a data before fetching aux hint.

Change-Id: I9792880dbc9d3705f3cdcf2b4d13b9c365278d4f