Add CLI for configuration mode. to generate VPP startup.conf
At least it should bind pci-address to an interface.
Proposed CLI `set (forward|data)-plane xxx`
```
set forward-plane pci-address xx:xx:0 interface eth1
set forward-plane pci-address xx:xx:1 interface eth2
set forward-plane cpu main-core 1
set forward-plane cpu core-workers 4-5
...optional
set forward-plane bridge br0 interface eth1
set forward-plane bridge br0 interface eth2
set forward-plane eth0 address x.x.x.x/x
```
Expected minimal /etc/vpp/startup.conf
```
unix {
nodaemon
log /var/log/vpp/vpp.log
full-coredump
cli-listen /run/vpp/cli.sock
gid vpp
}
api-trace { on }
api-segment { gid vpp }
socksvr { default }
cpu {
main-core 1
corelist-workers 4-5
}
plugins {
path /usr/lib/x86_64-linux-gnu/vpp_plugins/
plugin default { disable }
plugin dpdk_plugin.so { enable }
plugin linux_cp_plugin.so { enable }
plugin linux_nl_plugin.so { enable }
}
dpdk {
dev 0000:03:00.0 { name eth1 }
dev 0000:04:00.0 { name eth2 }
}
```