Fade task items when swiping out

As we have a fixed width for the task list now, we have to ensure that
we do not clip the task items when we swipe them out. In addition, we
should fade them out by the end of the swipe as the swipe end location
may still be on a visible part of the screen.

Bug: 131686863
Test: Go to landscape mode, swipe out tasks
Change-Id: If86136a9f9d47098a6dd5d355d3a99d540165c77