Tapping task icon in overview with scroll to it and open

Smaller devices or landscape with splitscreen can show more than one
task icon in overview. Tapping the icon when not in the middle will
scroll the task into the middle and open at the same time.

Change-Id: I0fe261e9a1b8ab6ad7e6c6ea64125a9c7b38da39
Fixes: 110371874
Fixes: 111446332
Test: splitscreen, overview in landscape, tap non-centered task icon