Potential fix for apps disappearing in launcher on system server crash

Throw RuntimeException to launcher if there was a RemoteException
from LauncherAppsService. This matches the behavior of previous
calls that were made to PackageManager that could have resulted
in a RemoteException if the system server was dying/dead.

Bug: 15687732
Change-Id: Ifda3fda209141b361a286fc033217acfa0ec196e