highlights(rust): distinguish between "for" in loops and impl_item

Fixes #3641

tests/query/highlights/rust/for.rs

@@ -0,0 +1,15 @@
+struct Foo;
+
+// Issue https://github.com/nvim-treesitter/nvim-treesitter/issues/3641
+// Distinguish between for in loop or impl_item
+impl Drop for Foo {
+    //     ^ @keyword
+   fn drop(&mut self) {}
+}
+
+fn main() {
+    for i in 0..128 {
+    // <- @repeat
+        println!("{i}");
+    }
+}