Stop using devdocs as source for current APIs and move to lib/apis.json

[stronk7]

Since Moodle 4.2 (see MDL-71096), we have all the APIs available in core @ /lib/apis.json.

So we don't need anymore to crawl them from dev docs, they should be available in code base always (4.2 and up) and can keep a copy for older versions bundled with the plugin.

This issue is about to make that switch.

Ciao :-)

[stronk7]

I'm closing this now because moodle-cs is taking on this for Moodle 4.2 and up, see moodlehq/moodle-cs#112

So we won't be implementing that here ever. Everything is being moved to moodle-cs, see moodlehq/moodle-cs#30

Ciao :-)