[Wi-Fi] Updates internal AccessPoint list upon onAccessPointsChanged

Updating access point list requires WifiTracker's AccessPoints and
WifiNetworkFactory's matching scan results. When WifiNetworkFactory
sends the matching scan results to NetworkRequestDialogFragment, if
WifiTracker still does not receive scan results, UI will not be
updated.
This CL is to update internal AccessPoint list from WifiTracker
upon onAccessPointsChanged callback to reflect results properly.

Bug: 140600730
Test: manual, robotests
Change-Id: I0f9814821b3d56f3c55f1e6419c8b7a03b03589e
Signed-off-by: Daichi Ueura <daichi.ueura@sony.com>