[AWARE] Add API to translate PeerHandle to MAC address

Add an internal only (protected) API which translates PeerHandle (id)
to the corresponding MAC address (if available). Useful for services
such as RTT whose public API accepts a PeerHandle, but whose backend
requires an actual MAC address.

Bug: 65015034
Test: unit tests + RTT integrated tests
Change-Id: I5e6f3fbc1d9aa67630024ed55326c9f11bd58395
4 files changed