This commit makes sure that a set of rocketmq workers are started for
each topic. Before this commit all actions for a rocketmq connector used
the same workers which all were bound to a single topic so all messages
got delivered to that topic regardless of the action configuration.
We should have automatic tests to check that the messages actually go to
different topics but this needs to go into another PR since we have to
deliver the fix fast and the rocketmq library does not support reading
from topics.
Fixes:
https://emqx.atlassian.net/browse/EEC-1006
Kjell Winblad