Add `try_recv` to `Eval`

[Sitin]

Feature Request

Add a "non-blocking" try_recv metod to Eval struct returned by document::eval.

Reasoning

This method can be useful when we want both send and receive from Eval.

[ealmloff]

The try_next method returns a future, it doesn't block the thread. If you need to do other work at the same time, you could use join or if you want to check if the future is ready without waiting, you can use now_or_never:

let res: Option<Result<String, _>> = eval.recv().now_or_never();

Would the try_recv you propose in this issue act any differently from eval.recv().now_or_never()?

[Sitin]

For two reasons. First, try_* is a general pattern found all over std and community libraries. This would create a predictable API. Second, Dioxus already uses evaluator.try_write in recv(). Why should we wrap it into a future for those library users who don't need this?