Use PermissionChecker with AttributionSource for BT location checks.

This changes the location checks in startScan and startDiscovery to
use PermissionChecker with the attribution source.

Bug: 183203469
Test: atest GattServiceTest
Test: atest AdapterServiceTest
Test: atest CtsPermissionTestCases:android.permission.cts.NearbyDevicesPermissionTest

Change-Id: I188317b938ab3002b8dd97607efd5912970667dd