[Wi-Fi] Support WifiTrackerLib in WifiDialogActivity

After this change, WifiDialogactivity supports both WifiTrackerLib and
SettingsLib because this is an exported UI component, some other APPs
(e.g., SetupWizard) still use SettingsLib.

Bug: 152571756
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.wifi.WifiDialogActivityTest
      manual
      In Wi-Fi Settings, manually add a Wi-Fi network.
      In SetupWizard, manually add a Wi-Fi network.
Change-Id: I87f477d905cc6ea34ef1afbfade3773920dad6eb