Show mobile data icon with carrier Wi-Fi level in Settings

- If carrier Wi-Fi is active then use carrier Wi-Fi level instead of
  mobile data level.

- If carrier Wi-Fi level is less than min-level, use min-level instead.

Bug: 222885558
Test: manual test
atest -c SubscriptionsPreferenceControllerTest \
         WifiPickerTrackerHelperTest

Change-Id: I46ba5129357bae47e5e44dcbbb26e6673581fdc8