Added GetState, GetManagedProperties, CreateNetwork methods to WiFiService. 
Initially implemented only to satisfy Networking Private Api browser_tests.
Moved hard-coded test data for NetworkingPrivateApiTest into fake_wifi_service.cc

BUG=267667

Review URL: https://codereview.chromium.org/100493002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238835 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238835