ovn-controller: Provide the option to set the datapath-type of br-int

ovn-controller: Provide the option to set the datapath-type of br-int

If the integration bridge is deleted, ovn-controller recreates it
but the previous datapath-type value is lost if it was set. This
patch adds the code in ovn-controller to set the datapath-type
if it is configured by the user in the 'external_ids:ovn-bridge-datapath-type'
column of OpenvSwitch table.

Acked-by: Mark Michelson <mmichels@redhat.com>
Signed-off-by: Numan Siddique <nusiddiq@redhat.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>