Add capport info to WiFi details(WifiDetailPreferenceController2)

Session expiration time and venue webpage can be obtained through the
captive portal API.

Test: make RunSettingsRoboTests \
      ROBOTEST_FILTER=WifiDetailPreferenceController2Test
      (Since WifiDetailPreferenceController2Test is ignore now,
      there is no test will be run in
      WifiDetailPreferenceController2Test)
Bug: 139269711
Change-Id: I80b93689539c6ba5edafa3d0029376deca7ac1f7