debian: Move OVSDB schema and ovsdb-tool to openvswitch-switch.

debian: Move OVSDB schema and ovsdb-tool to openvswitch-switch.

ovs-vswitchd in the openvswitch-switch package is tightly coupled to its
database schema.  During development, it's possible to change the schema
without changing the Open vSwitch version number, which makes it possible
for the openvswitch-switch and openvswitch-common packages to get out of
sync: openvswitch-switch requires the same version of openvswitch-common,
but if the version number doesn't get updated that has no effect.

Actually putting the schema and ovs-vswitchd (its primary user) in the
same package prevents them from getting out-of-sync.  This commit also
moves ovsdb-tool because that program often works directly with OVSDB
schemas and so there's not much point having it around without a schema to
work with.