PhoenixSwarm: produce extendable (communication, processing) statistics

The "daemons" of PhoenixSwarm should be able to report statistics on their communications and processing for logging and monitoring:

• number of received messages for each data type
• number of send messages, number of send messages with acknowledgment of receipt
• latency between send messages and received confirmation
• duration of processing for each data type
• allow to extend these generic statistics with custom values for processing specific information (eg number of good events, number of pixels per event, etc. or values required by DQ)

Tasks:

• clarify what information should be computed and send: statistics should be accumulated for a given amount of time (1 sec?) but still be detailed enough to not hide outliers behavior: average values, median values, quartiles? Computing these values should be negligible compared to actual daemons processing
• clarify how the implementation can allow custom daemons to extend the statistics with more values
• implement the generic statistics in PhoenixSwarm