Allow parentheses for short expressions

[aDogCalledSpot]

The braces look good if there's a lot of content but personally I like using the round parentheses if there isn't a lot of content.

e.g.

match State {
    State::Loading => html!(<Spinner />),
    State::Ready(props) => html!(<MyComponent ..props />),
}

compared to

match State {
    State::Loading => html! { <Spinner /> },
    State::Ready(props) => html! { <MyComponent ..props /> },
}

The question is what constitutes a "short" expression. I would suggest either fits in one line or is a self-closing tag. I prefer the previous to allow something like html!(<p>Hello World</p>).

[its-the-shrimp]

Thank you for reporting this, in v0.3.0 yew-fmt doesn't coerce parentheses into curly brackets