Compute total number of packets sent and received by type

Added a global static class that keeps track of the total number of packets sent and received during the last 24 hours by device type and packet type.

When displaying the stats, it sorts the results so that packets with the most packets sents/received show up first. This should help us catch issues like the one in !361 (merged) where a plugin goes rogue and decides to send thousands of packets.

The dialog shows raw packet type strings and it's not meant to be user-friendly, so I hid the option within Device -> Plugin Settings -> Plugin Stats and decided not to translate the text.