app/testpmd: add command for sample action

app/testpmd: add command for sample action

Add a new testpmd command 'set sample_actions' that supports the
multiple sample actions list configuration by using the index:
set sample_actions <index> <actions list>

The examples for the sample flow use case and result as below:

1. set sample_actions 0 mark id 0x8 / queue index 2 / end
.. pattern eth / end actions sample ratio 2 index 0 / jump group 2 ...

This flow will result in all the matched ingress packets will be
jumped to next flow table, and the each second packet will be
marked and sent to queue 2 of the control application.

2. ...pattern eth / end actions sample ratio 2 / port_id id 2 ...

The flow will result in all the matched ingress packets will be
duplicated and sent to the representor peer (VF or wire) on DPDK port 2,
and the each second packet will also be sent to E-Switch manager vport.

Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
Acked-by: Ori Kam <orika@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>