[syntax-errors] Tuple unpacking in for statement iterator clause before Python 3.9 (#16558)

Summary
--

This PR reuses a slightly modified version of the
`check_tuple_unpacking` method added for detecting unpacking in `return`
and `yield` statements to detect the same issue in the iterator clause
of `for` loops.

I ran into the same issue with a bare `for x in *rest: ...` example
(invalid even on Python 3.13) and added it as a comment on
https://github.com/astral-sh/ruff/issues/16520.

I considered just making this an additional `StarTupleKind` variant as
well, but this change was in a different version of Python, so I kept it
separate.

Test Plan
--

New inline tests.

crates/ruff_python_parser/src/parser/expression.rs

@@ -2130,7 +2130,10 @@ impl<'src> Parser<'src> {
             // rest = (4, 5, 6)
             // def g(): yield 1, 2, 3, *rest
             // def h(): yield 1, (yield 2, *rest), 3
-            self.check_tuple_unpacking(&parsed_expr, StarTupleKind::Yield);
+            self.check_tuple_unpacking(
+                &parsed_expr,
+                UnsupportedSyntaxErrorKind::StarTuple(StarTupleKind::Yield),
+            );
 
             Box::new(parsed_expr.expr)
         });