Add http.ipfilter plugin for Caddy

[regystro]

Hi. Would it be possible to add https://caddyserver.com/docs/http.ipfilter plugin? I think it's important security-wise.

Thank you.

[bestlibre]

I will not have the time to do it soon. If you can do it, a pull request is welcome. If possible, it should be an opt-in feature.