Apigen integration is mostly outdated

[davidsneighbour]

Most of the parameters of Apigen seem to be failing. An open issue (#177) implies that some of these deprecated parameters were outdated seven years ago. Would it make sense to remove Apigen support maybe completely (so users of Robo will do a simple CLI call to the script)? Or maybe removing most of the parameters and leaving the config parameter to allow configuration via neon-config-file only?

Basically, none of the current config parameters of Apigen are working or corresponding to existing Apigen parameters; only the config parameter (compared to the robo.li documentation) is doing its job.

Maybe this is a version-related issue. I realized that composer require apigen/apigen will load a version 4+, and the latest version seems to be a version 7+.

It's the only php-doc generator supported by robo.li. I think either fixing its implementation or create a more general inclusion (and adding tools like phpdox and phpdocumentor) would be useful/helpful.