sw test tool: improve packet diff

Signed-off-by: WATANABE Fumitaka <watanabe.fumitaka1@gmail.com>
Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
sw test tool: improve FlowStats diff

Signed-off-by: WATANABE Fumitaka <watanabe.fumitaka1@gmail.com>
Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
sw test tool: improve MeterStats diff

Signed-off-by: WATANABE Fumitaka <watanabe.fumitaka1@gmail.com>
Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>