apps: Added netperf3 module

This is multi-threaded netperf version that currently is capable to run
only TCP_STREAM and TCP_RR tests.

Reviewed-by: Tomasz Grabiec <tgrabiec@gmail.com>
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>