Add permission usage information

Applications will be able to add information to their uses-permission
elements about how the data protected by that permission is used.

Currently the system does not use this information, that will be done in
a follow up CL.

Test: atest PermissionUsageTest
Bug: 111207567
Change-Id: Ic168684cc800febc8fb3a3f807e1917f1f1585a4