(HitTest) Ensure we do not create Actor handles when using the hit-test callback

(HitTest) Ensure we do not create Actor handles when using the hit-test callback

[problem]      Whenever we call the hit-test callback, we create a temporary Actor handle which
               can be quite an expensive operation (as constructors are called). We HAVE to do
               this for public hit-testing, but we are paying the penalty on internal hit-testing
               as well.
[cause]        Using the same interface for public and internal hit-testing.
[solution]     Use a functor internally which uses a specialised functor with an Actor handle for
               external hit-testing and another functor for the internal hit-test which uses
               an Internal::Actor* so we do not pay the penalty of creating a handle then.

Change-Id: I7bb81265b9c03aa3c7a714f0dd2ceec22e6a997b
Signed-off-by: Adeel Kazmi <adeel.kazmi@samsung.com>