Support edge data introspection

[jonnor]

Would be picked up by Coordinator and forwarded over FBP runtime protocol to a client like Flowhub, to allow for interactive introspection of the data

On MQTT, can subscribe to all topics /* in Coordinator
On RabbitMQ, looks like we can use CC/BCC functionality
https://www.rabbitmq.com/sender-selected.html

[jonnor]

It may be interesting to have data on selected ports (or in future, matching data breakpoints) be persisted somehow. Could either be in a database (as unique events), a flowtrace file, or one could send them to a queue.

Related: https://github.com/jonnor/flowtrace/blob/master/doc/braindump.md

[jonnor]

Done since 0.10 for MQTT and RabbitMQ