Provide the jsonl logger extension for use with Asciidoctor converters

The build command (AsciiDoc converter) must provide a jsonl logger in order for the log integration to work. Since Asciidoctor does not currently provide a jsonl logger, one has to be provided. Rather than making every user who wants to to use this log integration carry around this extension, the exporter extension (or Assembler core) should bundle it until it is provided by Asciidoctor.

Instead of depending on a specific path inside the npm package, perhaps Assembler can rewrite a "magic" CLI option that it replaces with the right path. Something along the lines of:

-r log-adapter