app/testpmd: support raw encap/decap actions

app/testpmd: support raw encap/decap actions

This patch intend to support
action_raw_encap/decap [1] in a generic and convenient way.

Two new commands - set raw_encap, set raw_decap are introduced just
like the other commands for encap/decap, i.e. set vxlan.

These two commands have corresponding global buffers
which can be used by PMD as the input buffer for raw encap/decap.

The commands use the rte_flow pattern syntax to help user build the
raw buffer in a convenient way.

A common way to use it:

- encap matched egress packet with VxLAN tunnel:
testpmd> set raw_encap eth src is 10:11:22:33:44:55 / vlan tci is 1
	 inner_type is 0x0800 / ipv4 / udp dst is 4789 / vxlan vni
	 is 2 / end_set
testpmd> flow create 0 egress pattern eth / ipv4 / end actions
	 raw_encap / end

- decap l2 header and encap GRE tunnel on matched egress packet:
testpmd> set raw_decap eth / end_set
testpmd> set raw_encap eth dst is 10:22:33:44:55:66 / ipv4 / gre
	 protocol is 0x0800 / end_set
testpmd> flow create 0 egress pattern eth / ipv4 / end actions
	 raw_decap / raw_encap / end

- decap VxLAN tunnel and encap l2 header on matched ingress packet:
testpmd> set raw_encap eth src is 10:11:22:33:44:55 type is 0x0800 /
	 end_set
testpmd> set raw_decap eth / ipv4 / udp / vxlan / end_set
testpmd> flow create 0 ingress pattern eth / ipv4 / udp dst is 250 /
         vxlan vni is 0x1234 / ipv4 / end actions raw_decap /
         raw_encap / queue index 1 / mark id 0x1234 / end

[1] http://mails.dpdk.org/archives/dev/2018-October/116092.html

Signed-off-by: Xiaoyu Min <jackmin@mellanox.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>