Check BLUETOOTH_SCAN permission when performing scans from GattService.

This adds checks for the new BLUETOOTH_SCAN permission in GattService.

The app op is noted when the location app op was noted previously,
i.e. in the startScan and registerPiAndStartScan methods. Hence
checkForDataDelivery is used there, and checkPreFlight is used
elsewhere.

Checks of the BLUETOOTH permission will be updated in a future CL.

Bug: 183203469
Test: atest GattServiceTest
Change-Id: I8696009c4bedaf42e3ca96d91c5c4d42d879a802