Pandoc/Lua stack: call citeproc from our Lua stack

[cscheid]

We should be calling pandoc.utils.citeproc() in a Lua filter step instead of using a parameter outside of Pandoc, so that extensions/filters can target this step.

See #7642 (reply in thread).

[cderv]

For reference, known filter that requires this :

• https://github.com/tarleb/citation-backlinks (example of this reported at Quarto does not allow to add filters after citeproc processing, leading to uncorrect results #9726)
• https://github.com/pandoc-ext/multibib (gives warnings as mentioned in Support for multiple bibliographies #7642 (comment))
• https://github.com/odkr/pandoc-zotxt.lua (not processing correctly modified Metadata for citeproc to used citeproc settings in YAML metadata block: Problems when using pandoc-zotxt.lua filter #2294)

[TomBener]

This issue is also related #2294