Rename json::List to json::Array

Fixes #19010
@eddyb [I unprefixed the type aliases](https://github.com/frewsxcv/rust/commit/f60f650e2cbbb9a8275ff0a4f8a07801acecd486) and it appears [they are conflicting with the variants](https://gist.github.com/frewsxcv/e361a3d339d0441f3796). Am I doing something wrong here?