Enable printing of full contents of packets sent out of CPU port in switch log

[jafingerhut]

If you enable logging, and --dump-packet-data <max_debug_print_len_in_bytes>, and use the CPU port to send packets from the switch to the controller (i.e. P4Runtime API's PacketIn feature), and/or inject packets from the controller into the switch via P4Runtime API's PacketOut feature, you can find lines in the log that show the full contents of packets sent to and received from "normal ports" in the log, and also for PacketOut packets from the controller that are received by the switch on the CPU port.

However, the log appears not to include the hex dump contents of packets sent from the switch to the CPU port. I am creating this issue because it would be nice if the contents of such packets were included in the log.

Example that enables all necessary options, and exercises PacketIn and PacketOut packets, plus packets received on normal ports, and sent to normal ports:

• https://github.com/jafingerhut/p4-guide/tree/master/ptf-tests/registeraccess