Compares the address to the privat prefixes.
impl Ipv4Addr { fn is_private(self) -> bool }
The privat prefixes are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16