Make gloo::timer's future-based design like stdlib

[futursolo]

Summary

Make gloo::timer's future-based API like std / tokio.

Motivation

Why are we doing this? What problems does it solve?

This issue purposes to make gloo::timer's design more like Rust's standard library.

There was a similar discussion for the tokio library years ago about making the Tokio's sleep / timeout design to be similar to the standard library's design.

tokio-rs/tokio#2770
tokio-rs/tokio#2826

The rationale:

• It's more familiar with people coming from other Rust areas.
• The std::thread::sleep takes a Duration which is a better design than taking a number in millisecond in my opinion.
• gloo::timer::sleep(Duration::from_secs(1)).await is easier to understand and remember than gloo::timer::TimeoutFuture::new(1000).await for most people.

Detailed Explanation

async fn sleep(duration: Duration) {
    // ...
}

Drawbacks, Rationale, and Alternatives

Does this design have drawbacks?

It breaks compatibility.

Are there alternative approaches?

The current approach of gloo::timer.

Why is this design the best of all designs available?

This is a design that meets the expectation for people coming from both Rust and other common programming languages.

What prior art exists?

This is the design used by std and tokio.

[futursolo]

Sorry for filing an incomplete issue. I have updated the issue title and description.

[hamza1311]

I like this approach. How about we add a function for sleep in addition to the current API?

fn sleep(duration: Duration) -> TimeoutFuture {
    // ...
}

// somewhere else
sleep(Duration::from_secs(5)).await
// after 5 seconds