gesture_manager: Filter events we add hooks for
Gesture manager doesn't care about focus manager events, animation events,
and various other things it's currently hooking.
We can save a lot of pointer indirection nonsense by only paying attention
to events it can actually do something with.
Differential Revision: https://phab.enlightenment.org/D7764
Signed-off-by: Derek Foreman <firstname.lastname@example.org>