In gadget definition pages, we can currently specify scripts, styles and datas. The first two are reasonable. The third datas, which is not even a word (as data itself is plural), is used for JSON pages. With T340460, we'll probably have another one with no better name than vues.
Instead of all that, we should consider having just a single field pages. This is more similar to MediaWiki:Gadgets-definition where all pages are specified together. The page name suffix and content model can be used to decide if it's a JS/CSS/JSON/Vue page.