LUCENE-5969: move CFS to codec

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5969@1628996 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5969: remove back compat

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5969@1629001 13f79535-47bb-0310-9956-ffa450edef68