unawaited_futures should consider try {return future} as unawaited

[rrousselGit]

Describe the issue
When returning a Future inside async functions, when wrapped in a try block, that future won't trigger an unawaited lint

To Reproduce

Future<void> fn() async {
  try {
    return Future.value();
  } catch (e) {
    ...
  }
}

Expected behavior

The return future line should emit an unawaited_futures. And awaiting it or marking it as unawaited should make the issue disappear.

Additional context

This is a common mistake. The catch/finally blocks may not trigger correctly when the returned future is unawaited.

[lrhn]

It's a bug that return future; does not await the future (#44395).
As such, the linter is technically correct, it's the implementation that is wrong.

Haven't been able to make it impossible to return a future yet (dart-lang/language#870), which would force you to write the await.

[srawlins]

I think we can consider this a duplicate of #58279, or vice versa if we want to update unawaited_futures.

[srawlins]

Duplicate of #58234