app/testpmd: support multiple raw encap/decap

app/testpmd: support multiple raw encap/decap

In some scenarios, the raw_encap/raw_decap actions could be multiple in
one single flow (e,g. hirepin flow):

  ... actions raw_decap / raw_encap / raw_decap / raw_encap / ...

This requires the testpmd supports multiple raw_encap/raw_decap data
settings as well.

With the multiple raw_encap/raw_decap settings, the testpmd commands –
set raw_encap / set raw_decap will become:

  set raw_encap <index> <item pattern>
  set raw_decap <index> <item pattern>

And the actions – raw_encap/raw_decap also could optionally choose which
global raw_encap/raw_decap confs to be used by index:

  ... actions raw_decap index 1 / raw_encap index 2 / ...

If there is no `index` specified, the default index is 0:

  set raw_encap <item pattern>
  ... actions raw_decap / raw_encap / ...

which will use raw_encap index 0.

In addition to the set raw_encap/raw_decap commands,

  show <raw_encap/raw_decap> <index>
  show <raw_encap/raw_decap> all

are also introduced into in order to check which index is set and to
what.

Signed-off-by: Xiaoyu Min <jackmin@mellanox.com>
Acked-by: Ori Kam <orika@mellanox.com>