Allow customizing the struct properties name

[cecton]

This change will allow the user to customize the name of the Properties struct.
Most of the time the user won't care so the default will be as before but in
case they do care (when making libraries of components for example), this is
now possible.

use yew_autoprops::autoprops_component;
use yew::prelude::*;

#[autoprops_component(CoolComponent, CoolProps)]
fn cool_component(#[prop_or_default] test: &i8, smth: &usize) -> Html {
    println!("test: {}", test);

    html! {
        <div>
            <p>{ smth }</p>
        </div>
    }
}

impl CoolProps {
    fn foo() {
    }
}

[cecton]

Oops sorry i didnt see the check!

[valyagolev]

Released as 0.3.0. Maybe update the README too if you have the time ;-)