Include IPv6 DNS servers in wifi details

Test: as follows
    - built
    - flashed
    - booted
    - export ROBOTEST_FILTER=WifiDetailPreferenceControllerTest \
          make -j RunSettingsRoboTests
      RunSettingsRoboTests:
      RunSettingsRoboTests: Time: 19.821
      RunSettingsRoboTests:
      RunSettingsRoboTests: OK (37 tests)
      RunSettingsRoboTests:
    - make -j RunSettingsRoboTests
      RunSettingsRoboTests: ...........................
      RunSettingsRoboTests: Time: 424.847
      RunSettingsRoboTests:
      RunSettingsRoboTests: OK (2250 tests)
      RunSettingsRoboTests:

Bug: 65037256
Bug: 65467586

Change-Id: Icd3d09aa35c04101c41e2521b48e64f28f69ae29