ONC: Add orphaned ONC test cases to Validator unittest.

During removal of NetworkLibrary (r222615), several unittests for ONC import were removed without replacement.
This change adds most of these ONC files to the Validator unittest.

BUG=276291

Review URL: https://codereview.chromium.org/68523007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234826 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234826