Introduce new API for retrieving PNO scan results

Create a seperation of code paths for retrieving scan results from
single scan vs those from a PNO scan. This enables the underlying
implementation to return PNO scan results from the interface that most
recently completed the scans while ensuring no changes to the way single
scan results are returned to the framework.

Bug: 63148974
Test: Unit tests, on-device test for connecting to a network found by
Offload HAL during Pno scans

Change-Id: I6002f6df05e40fe24ff12f4a49599343578873f4
5 files changed