Fix the Wi-Fi detailed settings un-editable issue.

- The WifiEntry info might not be ready in early stage. (ex:
WifiEntry#canSetPrivacy())

- The Wi-Fi detailed setting listens to the WifiEntry callback to
refresh the preferences, it should first update the preference status to
be editable or not, and then display preferences to the UI.

- The privicy preference should be able to set back to selectable when
WifiEntry#canSetPrivicy() change from false to true.

Bug: 170148009
Test:
make RunSettingsRoboTests
ROBOTEST_FILTER=WifiNetworkDetailsFragment2Test
make RunSettingsRoboTests
ROBOTEST_FILTER=WifiPrivacyPreferenceController2Test

Change-Id: I48ca060e6b468232f19c82e9de0ce4fce39cba7f
Merged-In: I567b2b80163631a01d165c0ac5c0aba392e014ef