Launch GroupedTaskView from thumbnails

* Previously when starting the remote animation
we were relying on SplitPlaceholderViews to
animate into the proper place since we weren't
launching from the TaskView itself
* Now when launching from a GroupedTaskView,
we use the existing animation that handles that
animation in addition to showing the new split tasks

Fixes: 206608786
Test: Thumbnails animate from home -> overview -> launch
Change-Id: I1499ead7d90cd41e285ed0f4df66ea31f0dfbc95