[queens] Smooth out OVN backend

* add missing ovn control options file
* install networking_ovn package before db_sync
* set sync mode of ovn northbound OVSDB with neutron DB
* enable distributed floating IP support if DVR is turned on

Change-Id: I1ece368e8d763fa7c96b1853646e90d5c1fb11e0
6 files changed