Move {AnyNodeRef, AstNode} to ruff_python_ast crate root (#8030)

This is a do-over of https://github.com/astral-sh/ruff/pull/8011, which
I accidentally merged into a non-`main` branch. Sorry!

crates/ruff_python_formatter/src/expression/expr_attribute.rs

@@ -1,5 +1,5 @@
 use ruff_formatter::{write, FormatRuleWithOptions};
-use ruff_python_ast::node::AnyNodeRef;
+use ruff_python_ast::AnyNodeRef;
 use ruff_python_ast::{Constant, Expr, ExprAttribute, ExprConstant};
 use ruff_python_trivia::{find_only_token_in_range, SimpleTokenKind};
 use ruff_text_size::{Ranged, TextRange};