Use TouchDelegate to listen for icon view taps on RecentsView

Using a negative margin to move the icon view to stick out above
the task prevents that part sticking out from receiving touches.
They go directly through to RecentsView, which interprets it as a
touch to home.
Now we use a touch delegate that recents view passes touches to
before processing it directly.

Note we can't override should steal touches from children in
LauncherRecentsView because the icon view isn't actually seen
as a child of RecentsView if it's outside of the task view area.

Fixes: 159820339
Test: Touching anywhere on the icon works.
Scrolled to previous/next tasks and in different
rotations and verified tap registers correctly.

Change-Id: I4559c34b20079e06aac401e2c93ac36a74b653ea