Suspense boundaries/pure HTML out of order streaming/anyhow like error handling

[ealmloff]

This PR improves context based suspense by bubbling suspense to the nearest suspense boundary.

This allows you to handle suspense at a single boundary which makes it easier to show an unified loading UI.

It uses the current extension trait to return early when a suspended resource is encountered, but this now returns an error instead of None to avoid issues when the suspense is handled manually in the component.

// Suspense context
#[component]
fn Parent() -> Element {
    rsx! {
        ErrorBoundary {
            handle_error: |err| rsx! { div { {err} } },
            Suspense {
                pending: |suspense| rsx! { div { {suspense} } },
                Doggo {}
            }
        }
    }
}

#[component]
fn Doggo() -> Element {
    let download_progress = use_signal(|| 0.);
    let mut fut = use_resource(move || async move { download_model(download_progress).await })
        .suspend()
        // You can optionally add a hint for the suspense boundary to render
        .with_suspense_placeholder(move || rsx!("Downloading LLM... {download_progress}% done))?
        .throw()
        // You can optionally add a hint for the error boundary to render
        .show_with(|err| rsx!("hugging face is down 🙁: {err:?}"))?;

    todo!()
}

Breaking changes:

• This PR changes the Element type from Option to Result to make it easier to return errors early, and properly track the result of the component. Without this change, if you throw or suspend, handle it manually and then return None manually, dioxus will try to handle the suspense/error for you

Closes #1335
Closes #2389
Closes #2264

Stacked on top of #2226, #2437, #2444

[ealmloff]

Still some paper cuts here, but the initial version of suspense boundaries and component errors is working. Here are a few things I would like to improve in future PRs:

1. Server function errors don't automatically convert into CapturedError - Switching to a custom error type in server functions can fix this
2. Out of order streaming can cause large html streams if the page is large and updates are frequent - In the future we should try to patch just suspense boundaries if that is the only part of the UI that was updated

[ealmloff]

mounted events are working correctly, but effects currently run inside of suspended nodes instead of waiting for suspense to finish before running