sw test tool: Enable parsing a new 'ingress' format

The format is for continuous-sender.
sw test tool: Add support for sending packets continuously
sw test tool: Change egress/PACKET_IN processes to a method

For sharing by one-shot-sender and continuous-sender.
sw test tool: Change table-miss processes to a method

For sharing by one-shot-sender and continuous-sender.
sw test tool: Enable sending packets continuously