Wificond: Address bugs in handling Offload scans

Wificond: Address bugs in handling Offload scans

This CL addresses the following issues in handling of Offload HAL scan
results from the Offload HAL service
- Make cached scan results member variable a pointer so that the memory
for the vector can be allocated on the heap
- When an Async Error occurs in the Offload HAL service, switch to
performing PNO scans over netlink instead of letting it decide again.
- OffloadScanUtils convertToNativeScanResults() now needs to take in a
pointer to the vector that will store the scan results for retrieval.
- Populate tsf field fo the scanResult so that it doesn't get filtered
out by the framework
- Add logging to scan stats

Bug: 63148974
Test: Unit tests, on-device testing for ensuring we connect to an
available access point from screen off disconnected mode.
Change-Id: Ida507d857faa8ea6dbee362cf0116f8ca858963f