Don't restore persistent task to a stack until needed.

On boot-up we restore all persistent tasks to an activity stack.
This can cause issues with the activity stack supervisor when it
tries to make restored tasks with activities visiable when they
shouldn't be. Which ends up messing up the order of the recents
list. Now we don't restore persistent tasks to an activity stack
on boot-up. Instead we add the task to the stack when it is needed.

Also, fixes issue with not been able to launch task records with
activity records that were restored from an other device.

Bug: 18692762
Change-Id: Iad0e6635f8c5d1dab4d341feb3e7b06291a94739