App Circle Sidebar: Support for Configurable Trigger Region[1/2]

Change-Id: Ib89a98e607f48108b1a1fb54f00335a3bc4ff2e7
(cherry picked from commit d21d1c8a67471347d1cb62ae0b25a2f2dea56f22)

Conflicts:
	core/java/android/provider/Settings.java
	packages/SystemUI/src/com/android/systemui/appcirclesidebar/AppCircleSidebar.java