Move the cloud policy protobufs into the component.

This change moved chrome/browser/policy/proto/chromeos to
chrome/browser/chromeos/policy/proto, and chrome/browser/policy/proto/cloud to
components/policy/proto.

This enables the component code to use the cloud policy protobufs, so that iOS
can use cloud policy.

The old location is still kept temporarily until new git mirrors are set up
pointing to the new locations. A couple of PRESUBMIT scripts check that the
files are kept in sync.

BUG=271392, 327345
TBR=mnissler@chromium.org

Review URL: https://codereview.chromium.org/108563005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240108 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240108