Implement raw url SubMacros substiturors. TOFIX

Confused by what type attrs is.
https://github.com/asciidoctor/asciidoctor/blob/70fe46bf5c28ac37afbab3b654432eeedb0c27ef/lib/asciidoctor/substitutors.rb#L691

    attrs = parse_attributes(sub_attributes(m[3].gsub('\]', ']')), [])
    text = attrs[1] <= array? map with '1' as an entry?