Make creating AllAstNodeIter explicit.

This is to remove the ambiguity between calling iter on the specific structs like Document and calling iter on an AstNode by having an explicitly-named function to create the iterator.

src/parser/in_buffer_settings.rs

@@ -157,7 +157,7 @@ pub(crate) fn apply_in_buffer_settings<'g, 's, 'sf>(
 #[cfg_attr(feature = "tracing", tracing::instrument(ret, level = "debug"))]
 pub(crate) fn apply_post_parse_in_buffer_settings<'g, 's, 'sf>(document: &mut Document<'s>) {
     document.category = Into::<AstNode>::into(&*document)
-        .into_iter()
+        .iter_all_ast_nodes()
         .filter_map(|ast_node| {
             if let AstNode::Keyword(ast_node) = ast_node {
                 if ast_node.key.eq_ignore_ascii_case("category") {