Item12104: Move the log iterators to Foswiki::Iterator

By putting them in the Logger directory, configure makes them available
as logger implementations. Moving them to Iterator to get them out of
the way.

git-svn-id: http://svn.foswiki.org/trunk/core@17743 0b4bb1d4-4e5a-0410-9cc4-b2b747904278