Fun with Up navigation

For activities with a null taskAffinity, simply finish the current task.
(They probably shouldn't have specified a parentActivityName anyway.)

When launching into app info from ResolverActivity, launch the app info
page in the current task with FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET. Back
will return to the resolver, and Up will jump to Settings.

When launching into app info from RecentsPanelView or BaseStatusBar,
since this is a system affordance akin to notifications or widgets,
build the full task stack for the app info activity with
TaskStackBuilder and launch it as a new task.

Change-Id: I73b1941d0f52bd8b30382b5e17edd8ceb058c70d