There are 3 sources:
- core, a public method in a languages/ class
- config, not exposed through a public method, but in IS
- Wikibase extension, not exposed through a public method, but in WikibaseRepo class
We should provide an API method to get these languages as a languace code / autonym JSON array.
@Harmonia_Amanda wanted to get such the list and the three sources to mix is a little confusing.