Add thumbnails to the task view.

This CL adds thumbnails to the task view so that the labels are next to
a combined view with the thumbnail to the left and the icon at the
bottom right.

Due to the way launcher creates shadows on icons, the icons are actually
smaller than desired, so there need to be further changes to determine
the appropriate scale in order to have the bottom of the icons be flush
with the snapshot's bottom.

Bug: 114136250
Test: Launch l3GoIconRecents, see thumbnails + icon
Change-Id: Ief1cf54634544b9e310c68588998901871efda44