For context, see https://github.com/neovim/neovim/pull/24738. Before
that PR, Nvim did not correctly handle captures with quantifiers. That
PR made the correct behavior opt-in to minimize breaking changes, with
the intention that the correct behavior would eventually become the
default. Users can still opt-in to the old (incorrect) behavior for now,
but this option will eventually be removed completely.
BREAKING CHANGE: Any plugin which uses `Query:iter_matches()` must
update their call sites to expect an array of nodes in the `match`
table, rather than a single node.