[ECM] Make ACCESS_RESTRICTED_SETTINGS SystemApi

Make the following symbol SystemApi:

- AppOpsManager.OPSTR_ACCESS_RESTRICTED_SETTINGS

These will both need to be accessed from the Permission module
V+, so will need to be SystemApi.

This change is for the Enhanced Confirmation Mode updates for V project.

Bug: 310655061
Test: manual
Change-Id: Ia093aa3dc3f10c3c91e9f196d2f8dea94bab3099