Adding SafetyCenter APIs to PermissionController framework.

This implements a basic version of go/angel-in-mainline-api, only
for the bits that are unlikely to change (i.e. introduce the ability
for safety sources to provide data to the safety center).

Test: ag/16284943
Bug: 203098016
Bug: 203586427
Bug: 203400898
Change-Id: Ib9f3ee77bdde0eb33ec5245740ab3b8663675c90