passpoint-r2: change the return type of getAllMatchingWifiConfigs

This change is required to show the signal level associated with service
name on UI for installed passpoint profile as picking strongest one up
from matching scanResults.

In order to get a map that consists of WifiConfiguration and a list of
ScanResults, three steps are required.

1) Gets a map that consists of FQDN(Fully Qualified Domain Name) of
a matching Passpoint profile and a list of ScanResults.
2) Gets a list of WifiConfigurations for Passpoint profiles matched a
provided list of FQDN.
3) Creates a new map that consists of WifiConfiguration and a list of
ScanResult.

Bug: 119514793
Test: ./frameworks/base/wifi/tests/runtests.sh
Test: tested with R1 AP for installing profile and R2 AP for connection
Change-Id: I0d56dbdddae4e365b909b9c8f3eff3b0121dc5de
Signed-off-by: Ecco Park <eccopark@google.com>