New port: textproc/pup: Command-line jq-like HTML parser using CSS selectors

pup is a command line tool for processing HTML. It reads from stdin, prints
to stdout, and allows the user to filter parts of the page using CSS
selectors.

Inspired by jq, pup aims to be a fast and flexible way of exploring HTML
from the terminal.

WWW: https://github.com/ericchiang/pup

Reviewed by: krion
Approved by: krion (mentor)
Differential Revision: https://reviews.freebsd.org/D19378