ONC: Allow multiple CA certificates.

So far only a single CA certificate was supported for EAP/IPsec/OpenVPN. Instead, we now support multiple CA certs. These are provided as a list of GUID references to CA certificates in the toplevel "Certificates" section.

BUG=276291
R=armansito@chromium.org, davidroche@chromium.org

Review URL: https://codereview.chromium.org/68343010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240874 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240874