Bless Component Trait - #3435

This PR simplifies the deprecated Component trait and widget implementation by removing self-references and other hacks.

As a result, the component widget is now undeprecated and can be officially leveraged again to create reusable widgets as embeddable iced apps.

The main API difference that allowed for these improvements is the new Component::view signature:

pub trait Component<'a, Message, Theme = crate::Theme, Renderer = crate::Renderer> {
    // ...
    fn view(&self, state: &Self::State) -> Element<'a, Self::Event, Theme, Renderer>;
}

The view of a Component can no longer borrow state from the component state itself, but just the application.