GitLab

This CL does the following:
* Eliminates auto connect glue code
* Elim SetManaged* helpers
* Converts StaticIPConfig, SavedIPConfig, and WebProxyAutoDiscoveryUrl
  properties from Shill to ONC
* Uses ManagedNetworkConfigurationHandler::GetManagedProperties in
  internet_options_handler.cc to get (almost) all properites. The
  remaining properties will require additional translation and/or design

BUG=279351

Review URL: https://codereview.chromium.org/509643003

Cr-Commit-Position: refs/heads/master@{#293816}