feat: use go-flags

[ocervell]

Consider using https://github.com/jessevdk/go-flags to have nicer options sets (for instance for headers, short flag -H, long flag --header)

[edoardottt]

I've always been using https://github.com/projectdiscovery/goflags. Do you see something missing there?

[ocervell]

Oops sorry, that's the one I meant :D
Maybe we just need short versions of the flags then !