Add tests for PermissionMonitor

Add more tests to PermissionMonitor to verify the functionality related
to INTERNET permission and UPDATE_DEVIE_STATS permission. Modified some
of the class design of PermissionMonitor so that it is easier to test
the new functionalities.

Bug: 111560570
Test: PermissionMonitorTest

Change-Id: Ic5585f337db5de48e2f87bf4f01ed7d85c349827