init: Add "partition.*.verified" properties to the property service.

These are intended to be used by the rest of the system as weak
indicators that the corresponding partition is verified. For
instance, if the "partition.system.verified" property is set then
using `adb remount` would be unwise.

These should not be used as the basis for security decisions.

Change-Id: Ibea4c13abd54f46537e2a406774412c25918b24d