`prefer_final_parameters` should not flag params used in destructured patterns

Child issue of https://github.com/dart-lang/sdk/issues/58837 I suppose.

I think there should be a test case like:

```dart
void f(int two) {
  var list = [1, 2, 3];
  var [_, two, _] = list;
}
```

in which the lint rule would _not_ report that final should be preferred for `two`.