Fix modification of WifiDialog doesn't take effect on details page

When clicking modify menu option in detiails page, modification on
metered or privacy preferences in the WifiDialog does not effect
back to details page but only changing internal data of WifiDialog.
Adding callback to update those two preferences.

Bug: 130775713
Test: make RunSettingsRoboTests -j32 ROBOTEST_FILTER=com.android.settings.wifi.details.WifiDetailPreferenceControllerTest
Change-Id: I74bfa5a9581dfae73894c3e9f73d1069a36fd16b