relayd protocol: reply path for close chunk and create session 2.11

Since the relay daemon is expected to be able to move the target
destination of the trace, reply the chunk and session path so session
can have relevant data rather than guessing their location.

The session daemon now use this information to send the path back to
the client for rotation and destroy commands, as well as for
rotation completion notifications.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>