Add formatting of type alias statements (#6162)

Part of #5062 
Extends https://github.com/astral-sh/ruff/pull/6161
Closes #5929

crates/ruff_python_formatter/src/lib.rs

@@ -188,6 +188,7 @@ impl Format<PyFormatContext<'_>> for NotYetImplemented {
 pub(crate) struct NotYetImplementedCustomText(&'static str);
 
 /// Formats a placeholder for nodes that have not yet been implemented
+#[allow(dead_code)]
 pub(crate) const fn not_yet_implemented_custom_text(
     text: &'static str,
 ) -> NotYetImplementedCustomText {