Multiplex and output-dir

See, specifically, the comment on relative paths.

There are two conflicting goals:

• for the file to render correctly, the -speaker.html file needs to live in the same directory as the audience file (because of relative paths).
• if we put the file in the same directory, then there's a large risk that users will accidentally publish the speaker file, and that's really not good (anyone with access to the content of -speaker.html can control the presentation).

I don't know exactly how we could solve this, but the current situation doesn't seem that great.

Discussed in https://github.com/quarto-dev/quarto-cli/discussions/4718

^{Originally posted by jkub6 March 8, 2023}
All of the *-speaker.html files generated by revealjs multiplex don't end up in the output-dir directory specified in _quarto.yml.
Ideally (for me) they would end up right beside the client *.html presentation files. Instead, they remain beside the .qmd files.

Is this expected behavior? If so, is there a way to configure the output directory for these files?