Register .adoc/.asciidoc as AsciiDoc in the language catalog (backend registry and in-memory backend) with // line comments, and add a lightweight CodeMirror stream mode for headings, attributes, delimited blocks, emphasis, inline code, URLs and comments. Refs #708.
Co-authored-by: Bl0ck154 <36800583+Bl0ck154@users.noreply.github.com>