Open SensorPrivacy and WRITE_SECURE_SETTINGS to PC

Ensure the PermissionController can receiver the WRITE_SECURE_SETTINGS
permissions, to allow it to control location enable state. Open
SensorPrivacy APIs to @SystemApi. Also updates a SystemUI string
description to point to another string in PermissionController, which
should be kept in sync

Test: Build
Bug: 194816787
Change-Id: If4a45339449cc392eed28e33453c74a3b10988b4