Make PermissionManager use lists

... as requested per API review.

- Sets require iteration via iterators
- Sets are more expensive to construct
- The advantage of sets (faster .contains) is not used
- The system ensures uniqueness of the entires in the list

Test: Built
Bug: 116798569
Change-Id: I2c3b5c6801b78e0bf942073bde1e90299aee39f6