Hide edit menu if network is uneditable

- Screenshot:
  https://screenshot.googleplex.com/3BhZRBrmQXjeaGL

Bug: 161896161
Test: manual test
make RunSettingsRoboTests ROBOTEST_FILTER=WifiNetworkDetailsFragment2Test

Merged-In: I47ea2cf19e178eff48f23e56903d0daa4ef8fa28
Change-Id: I47ea2cf19e178eff48f23e56903d0daa4ef8fa28
(cherry picked from commit b7dbd3a9)