system-traffic: Add 5 new tunnel tests that don't need native linux modules

system-traffic: Add 5 new tunnel tests that don't need native linux modules

Introduce 5 new tests that don't require native gre or erspan tunnels but
sends simulated raw packets.

These tests are supposed to only run for kernel version from 3.10.x to 4.15.x
where compatible gre is being used by OVS kernel module.

Signed-off-by: Yifeng Sun <pkusunyifeng@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Tested-by: Greg Rose <gvrose8192@gmail.com>
Reviewed-by: Greg Rose <gvrose8192@gmail.com>