Support the use of Store

[LukaOber]

I would like to use Store in thaw components. With Store you can get() and set() the value separately. But it does not expose this as normal ReadSignal and WriteSignal. So we can't simply use them with thaw (I think).

Something like this.

#[derive(Debug, Store, Clone)]
struct StoreInfo {
    my_str: String,
}

#[component]
fn store_example() -> impl IntoView {
    let store = Store::new(StoreInfo {my_str: String::from("test")});
    
    view! {
        <Field label="Label">
            <Input value=store.my_str()/>
        </Field>
    }
}

[tqwewe]

I'd just like to share this commit I've made on a local fork:
tqwewe@83889f7

I think instead of using a store value directly like this, instead it should be more targeted towards Field in leptos 0.7. Store is more for a complex data structure, whereas field is a single field within a store. Field also implements From<Store>.

There is one issue with my commit on line 146 where Field doesn't implement Update, however this should be fixed with leptos-rs/leptos#3257