Macro impl_page_walk

macro_rules! impl_page_walk {
    ($S:ty, $T:ty, key_name = $key_name:tt) => { ... };
}

Available on crate feature catalog only.

Support for traversing paginated response values that look like:

{
    $key_name: [$T, $T, ...],
    next_page_token: "token" or null,
}