[Wi-Fi] Apply WifiTrackerLib objects in Wi-Fi Slice

This change uses WifiTrackerLib's WifiPickerTracker & WifiEntry
to replace SettingLib's WifiTracker & AccessPoint.

This change includes

1. WifiScanWorker has the callbacks similar to a lifecycle component
   but it's not a lifecycle component. Let WifiScanWorker implements
   LifecycleOwner and provides #getLifecycle() for WifiPickerTracker.

2. Remove captive portal related code because WifiEntry#connect will
   handle captive portal login if it's necessary.

3. Create WifiSliceItem to wrap WifiEntry because WifiEntry is an
   abstract object and it does not provide copy constructor.
   Without copy construcor, Wi-Fi Slice may show unexpected information
   when a WifiEntry is updated.

Bug: 155613549
Bug: 152571756
Test: make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.wifi.slice
      make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.wifi
Change-Id: I2d66ea4905daca3244ec4cf8f2935cda817480b1