Issue Description: Can policy-based routing and source NAT concurrently
work on an NE40E?
If traffic matches both policy-based routing and source MAT, only source
NAT takes effect. If both policy-based routing and source NAT need to take
effect, run the redirect ip-nexthop command on the NAT instance.
[~HUAWEI] nat instance cpe1 id 1
In the inbound direction,
outgoing traffic is redirected to the next hop.
In the outbound direction, incoming traffic is directed to the next hop.