Fix several hit issue for offscreen rendering

Fix several hit issue for offscreen rendering

 - Previous implementation
   - MappingActor is not hittable by default, but it was used to check
     whether it is hitted from OnScreen RenderTask or not in HitTestRenderTaskList.
   - There is nothing to check the layer including MappingActor is consuming hit.

 - Current implementation
   - For the OnScreen hit result, check whether there is a mappingActor of OffScreen
     hit results that can be hit in front of the OnScreen hit result.
     If it is, returns the OffScreen hit results.
   - If the OnScreen hit result is layer and the layer consumes hit(the layer must
     not be hittable), returns the OffScreen hit results.
   - If there is no hit in OnScreen but there are hit results from OffScreen
     RenderTask, returns the top OffScreen hit results.

Change-Id: I2788ed90dbe0145b4c263c371353b201c65c2a80
Signed-off-by: Seungho Baek <sbsh.baek@samsung.com>