remove quick replies: find corresponding WFR node

[fagiothree]

When removing quick replies from a send_msg node at the moment the corresponding WFR node is only identified finding the direct child node of the send_msg node. What happens if there is another node in the middle? there is nothing to check that the child node is actually a WFR node and to give a warning/error if it is not.

When looking for the WFR node we consider the first grandchild that is a router and then check if it is a WFR, otherwise throw an error.