Store data on if a mirror is anycasted (ipinfo)

The `ipinfo.io` database provides data on if an IP is anycast. We should store this in the database for future use (internal/publish it on the mirrors page?).

```
Anycast Information

curl ipinfo.io/8.8.8.8?token=$TOKEN

{
  "ip": "8.8.8.8",
  "hostname": "dns.google",
  "anycast": true,
  "city": "Mountain View",
  ...
}
```

* https://ipinfo.io/developers/data-types