Replace Bluetooth reflection usages with impl @hide API.

Since we are targeting Android T and above, the reflection limitation
of AdvertisingSet#getOwnAddress() only works when targeting Android O
below. This change use "framework-bluetooth.impl" to access @hide APIs
in "framework-bluetooth" just like SL4A does:
https://cs.android.com/android/platform/superproject/+/master:external/sl4a/Common/Android.bp

This change also replace some constants with @SystemAPI usages.

Test: Maunal launch NearbyFastPairProviderSimulatorApp and pair with mainline FP seeker
Test: http://recall/-/cycSROwIosTzHgYDSIqPXl/fAWLYYQQMVCw0QWuefBU7v
Bug: 214015364
Ignore-AOSP-First: nearby_not_in_aosp_yet
Change-Id: Iedd22c05803e93da529936f03f911c0e647e84ec
9 files changed