Created an preference in Apps & Notifcations page as the entry point for
apps that are hibernated. Also added a switch preference in AppInfo page
for users to exempt an app from hibernation.
Bug: 181172051
Test: HibernatedAppsPreferenceControllerTest;
HibernationSwitchPreferenceControllerTest;
AppInfoDashboardFragmentTest
Change-Id: I72a90ab391cd521150fc155a6d9c67c846b7360d
Based on the Android S design, move additional settings preference
above the Notifications preference and use SpacePreference to draw
the horizontal divider below AppButtonsPreference since the additional
settings preference is only visible by condition.
Also remove initialExpandedChildrenCount to expose all preferences.
Bug: 174964524
Test: robotest & visual with turning on/off silky home
Change-Id: Ife1d37820e44f8e12af4ed37ed66a29281366b50