This is to unblock early development on VisualEditor support for wikifunctions, by allowing parsoid to generate "real looking" markup for the new parser function.

The basic idea is to match the proposal in T373253#10278573 by:

• add mw:ParserFunction to the typeof
• change 'target: function' to 'target: pf'
• split the first parameter from the name (this is an existing parsoid misfeature) (https://gerrit.wikimedia.org/r/c/mediawiki/services/parsoid/+/820243)

That would let you write {{#anything}} on your local wiki and get parsoid markup which should generate the right markup to trigger your VE code. In particular, adding a ParserFirstCallInit handler to your LocalSettings.php which did:

$parser->addFunctionHook('function', static function($parser, ...$args) { return "placeholder" });

ought to be sufficient to generate the "correct" output markup for {{#function:1|2|3}} and thereby unblock work on VisualEditor support for this markup.

This is *not intended to be production-ready* code. This changes the markup for *all* parser functions, which would not be a safe thing to enable on production wikis. This is just a development tool, to bridge the gap while we write the "real" Parsoid registration/etc support.