Rewritten differently to address the issue where it only solved the case where the argument list starts on the tag line (which is highly likely, but not guaranteed) as per @elextr comment.
Now, it skips fold levels that look like being introduced by parentheses. It might be slightly problematic if a language doesn't fold on parentheses yet has a fold level that so happens to match perfectly just as if it did. I doubt we would see that, but if it's a problem we could restrict the extra checks to `LexCPP` (or any other that folds on `()`).