Include sessions in format_status/1

Include monitored session pids in format_status/1 of rabbit_amqp_writer.
They could be useful when debugging.
The maximum number of sessions per connection is limited, hence the
output won't be too large.

Author: ansd

deps/rabbit/src/rabbit_amqp_writer.erl

@@ -148,12 +148,15 @@ format_status(Status) ->
       fun(#state{sock = Sock,
                  reader = Reader,
                  pending = Pending,
-                 pending_size = PendingSize}) ->
+                 pending_size = PendingSize,
+                 monitored_sessions = Sessions
+                }) ->
               #{socket => Sock,
                 reader => Reader,
                 %% Below 2 fields should always have the same value.
                 pending => iolist_size(Pending),
-                pending_size => PendingSize}
+                pending_size => PendingSize,
+                monitored_sessions => maps:keys(Sessions)}
       end,
       Status).