INT-2856:Add support for adding/removing individual recipients to the Re...

Add support for adding/removing individual recipients to the RecipientListRouter
There should additional JMX operations useful for JMX. See `MappingMessageRouterManagement`.
I mean these:
````java
@ManagedAttribute
Map<String, String> getRecipients();

@ManagedOperation
void replaceRecipients(Properties recipientMappings);

@ManagedAttribute
void setChannelRecipients(Map<String, String> recipientMappings);
````
and see `ControlBusTests#testRouterMappings()`