Grant only the requested permissions

If an app requests a permission in a group we were auto granting it all
permissions from the group declared as used by the app. The intended
behavior is that we grant only the requested permission and requesting
a permission from a group where a permission is already granted results
in an auto-grant. The intended behavior was to prevent coding around
permission groups which a volatile by design. Now if apps target SDK
above M we provide the intended behavior, otherwise for apps targeting
M we provide an unchenged behavior.

bug:28347872

Change-Id: I493714b2c2581340b01b12ce6fedf80f9d3deec5