sw test tool: Support OFPGroupMod (type=ALL)

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
sw test tool: Support OFPGroupMod (type=SELECT)

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>
sw test tool: Support OFPGroupMod (type=INDIRECT)

Signed-off-by: Yuichi Ito <ito.yuichi0@gmail.com>