ekncontent: Log EkncQueryObject and XapianQuery representations
ekncontent: Log EkncQueryObject and XapianQuery representations

For debugging purposes, we should log all the query parameters as well as
what sort of Xapian queries they are turned into.

https://phabricator.endlessm.com/T20449

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib