Use AttributionSource when checking BLUETOOTH_SCAN permission.

This uses the AttributionSource for scan permission checks in
GattService scanning methods and AdapterService discovery methods.

The attribution source is also used to determine whether location
permission has been renounced, in which case location checks
will not be performed.

Changing the location checks to use the attribution source will
be done in a follow-up CL.

Bug: 183203469
Test: atest GattServiceTest
Test: atest AdapterServiceTest
Test: atest CtsPermissionTestCases:android.permission.cts.NearbyDevicesPermissionTest
Change-Id: Ia28e202443bb216303752ac969c1441eda6863f0