Ensure Taskbar stashes when launching an app from folder

We use the folder closing callback to trigger a call to stash the
taskbar if an app was launched. We can check whether an app was launched
from a folder based on whether a folder's view is open when
an app is launched. This ensures that the taskbar only stashes after the
folder is done animating.

Flag: NA
Fix: 295296529
Test: Launched an app in a folder on taskbar. Also ensured that other
taskbar behavior remains unchanged.

Change-Id: Ib5a797186978ee960e44b6b62c833eead03bccd0