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

Merged-In: If15181d557e9abce75111a6e1fff4e12586d7dbc
Merged-In: I55fbd611fee9f17215412a76b480cdee96f62b32
Change-Id: Icd3d09aa35c04101c41e2521b48e64f28f69ae29
(cherry picked from commit 9adc5887)