ofproto/trace: Add support for tracing conntrack recirculation

ofproto/trace: Add support for tracing conntrack recirculation

Previously, a user need to run ofproto/trace multiple times to derive the
final datapath actions if a flow hit conntrack actions that involves
recirculation. To improve the usability of ofproto/trace, in this patch,
we keep track of the conntrack actions, and automatically run the
recirculation process so that a user only need to execute the ofproto/trace
command once. Currently, this patch sets the default ct_state as
trk and new in the automatic recirculation process. A following patch
will provide an option to customize ct_state.

Signed-off-by: Yi-Hung Wei <yihung.wei@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>