Fix html5/block_listing – use data-lang attribute and highlightjs

Implements [this](https://github.com/asciidoctor/asciidoctor/commit/7d5a1744aa254ac8f04b07beb3056d591e65646e) and [this](https://github.com/asciidoctor/asciidoctor/commit/0e80e3b563a12f2109e1b6f6783dc3d7a6870043) changes from the built-in.