Navigation fixes for Settings

Change quick-entry points to Settings to have taskAffinity="",
excludeFromRecents="true", and no parentActivityName.

This makes the various quick shortcuts more standalone; their task
state does not persist and they have no Up navigation available. As
most shortcuts do not launch these activities with
FLAG_ACTIVITY_TASK_ON_HOME, Back will return the user to the previous
task.

This does not affect the "real" versions of these settings screens as
navigated to through the front door of the Settings app; those screens
are reached through SubSettings instances with specific fragments
added.

Bug 7276291

Change-Id: I7864437277601a3f6b6beded44a5edfd4636010c