Add a new family-specific syntax for tor_addr_parse_mask_ports
By default, "*" means "All IPv4 addresses" with tor_addr_parse_mask_ports, so I won't break anything. But if the new EXTENDED_STAR flag is provided, then * means "any address", *4 means "any IPv4 address" (that is, 0.0.0.0/0), and "*6" means "any IPv6 address" (that is, [::]/0). This is going to let us have a syntax for specifying exit policies in torrc that won't drive people mad. Also, add a bunch of unit tests for tor_addr_parse_mask_ports to test these new features, and to increase coverage.