Implement OP_SYSTEM_EXEMPT_FROM_POWER_RESTRICTIONS exemption

OP_SYSTEM_EXEMPT_FROM_POWER_RESTRICTIONS details:
* An app with this appop will be made exempt from all
  power restrictions, including app standby and doze.
* In addition, the app will be able to start fgs from
  the bg, and the user will not be able to stop fgs
  run by the app.

Changes:
* Implement the OP_SYSTEM_EXEMPT_FROM_POWER_RESTRICTIONS

Bug: 246330879
Test: atest PowerAllowlistBackendTest

Manual testing:
- Give OP_SYSTEM_EXEMPT_FROM_POWER_RESTRICTIONS appop to TestDPC app
- Verify the app can start fg services from the bg
- Verify fgs started by the app cannot be stopped
- Verify the app cannot be put into background restricted via Settings

Change-Id: If9e76076c59195f1e6e5f3eee3c8e7a0c754d8de

src/com/android/settings/applications/AppStateAppBatteryUsageBridge.java

@@ -96,7 +96,7 @@ public class AppStateAppBatteryUsageBridge extends AppStateBaseBridge {
         // Unrestricted = AppOpsManager.MODE_ALLOWED + allowListed
         // Optimized = AppOpsManager.MODE_ALLOWED + !allowListed
 
-        boolean allowListed = mPowerAllowlistBackend.isAllowlisted(pkg);
+        boolean allowListed = mPowerAllowlistBackend.isAllowlisted(pkg, uid);
         int aomMode =
                 mAppOpsManager.checkOpNoThrow(AppOpsManager.OP_RUN_ANY_IN_BACKGROUND, uid, pkg);
         @OptimizationMode int mode = MODE_UNKNOWN;