scripts: port alpine-conf's setup-proxy and setup-dns

[TheKingFireS]

I found it very useful for Termux, so I ported it. I removed some Alpinism things.
I also credited their works.

I tested it and it worked as intended.

[sylirre]

Unlike Linux distributions resolv.conf had different usage scope on Termux and works only for programs with internal DNS resolver. Everything else uses Bionic hostname resolution methods.

termux-setup-dns can be very confusing.

Furthermore proxy setup also used only by programs and networking libraries which look up relevant variables. This is not a system standard way of setting up proxy.

[TheKingFireS]

Unlike Linux distributions resolv.conf had different usage scope on Termux and works only for programs with internal DNS resolver. Everything else uses Bionic hostname resolution methods.

termux-setup-dns can be very confusing.

Fair.

Furthermore proxy setup also used only by programs and networking libraries which look up relevant variables. This is not a system standard way of setting up proxy.

Hm, but this is only quicker way to use proxy in Termux as Termux doesn't use Android system's proxy. But I agreed with you.