Scoped css

[mcmah309]

Closes #1096

Implements scoped css.

Revives and fixes the broken css_module! macro. Implementing a css recursive descent parser and a cleaner macro interface.

e.g.

use dioxus::prelude::*;
fn app() -> Element {
    styles!("/assets/styles.css");
    
    rsx! {
        div { class: Styles::container,
            button { class: Styles::button, "Click me" }
            span { class: Styles::global_class, "This uses global class" }
        }
    }
}

/assets/styles.css

.container {
    background-color: lightblue;
    padding: 20px;
    border-radius: 8px;
}

:global(.global-class) {
    color: red;
    font-weight: bold;
}

.button {
  color: blue;
}

Used css

.container-e1e1ad32 {
    background-color: lightblue;
    padding: 20px;
    border-radius: 8px;
}

.global-class {
    color: red;
    font-weight: bold;
}

.button-e1e1ad32 {
  color: blue;
}