Change CLI to more understandable in VPP context
Static
```
set vpp nat44 static rule 10 **external** address '192.168.122.53'
set vpp nat44 static rule 10 **inside**-interface 'eth2'
set vpp nat44 static rule 10 **outside**-interface 'eth0'
set vpp nat44 static rule 10 **local** address '200.64.0.10'
```
Source
```
set vpp nat44 source outside-interface 'eth0'
set vpp nat44 source inside-interface 'eth2'
```