Added a new "retailDemo" protection level.

Permissions that have the new wellbeing protection flag will be granted
to the retail demo app, as defined by the OEM in the system resource.

The PACAKGE_USAGE_STATS permission is updated to use the retailDemo
flag.

Bug: 146043112
Test: atest CtsPermission2TestCases:PermissionPolicyTest
Change-Id: I30b451e6e88a4d65af5e5f774bcd30a14721a8a9