More AttributionSource plumbing.

To prepare for future work which will plumb AttributionSource values
through all remaining AIDLs, we need profiles to interact directly
with the specific BluetoothAdapter they were created from.  This is
how we'll ensure that the relevant AttributionSource can be chained
down from the original Context they're obtained from.

This change also marks getDefaultAdapter() as deprecated to clearly
communicate that BluetoothManager.getAdapter() is the best-practice
path to obtaining a correctly scoped BluetoothAdapter instance.

Bug: 183626112
Test: atest BluetoothInstrumentationTests
Change-Id: I1e15170d7679019bbb6e396279d6e633e3dad4d6