Respect past user choices in permisson review UI

In a permission review mode we show UI for the user to review
new permissions for apps that do not support the new runtime
permission model. The review is shown on an app launch. It is
possible for the user to modify permissions in the settings
UI before launching an app.

This change ensures that the default value in the review UI
reflects the user choice in settings. Specifically, the review
UI shows the permission toggle in a granted state if the user
expressed no opinion or granted the pemrission in settings
(initially permissions are shown as revoked in settings as a
review is pending - granting a permission from settings doesn't
void the pending review). However, if the user grants and then
revokes a permission in settings, (expresses an opinion the
pemrission should be revoked) the default state of the permission
toggle is off.

bug:26741436

Change-Id: Iae6ae497dfba46ba1399fbf66fb60e70c37f0420