spread attributes not merged with existing class or style attributes

**Problem**

Spread attributes are not merged with existing `class` or `style` attributes.

**Steps To Reproduce**

Steps to reproduce the behavior:

running this modified `spread.rs` example for minimal reproducibility:

```rs
use dioxus::prelude::*;

fn main() {
let dom = VirtualDom::prebuilt(app);
let html = dioxus_ssr::render(&dom);

println!("{}", html);
}

fn app() -> Element {
rsx! {
SpreadableComponent {
class: "class2",
left: 1,
}
}
}

#[component]
fn SpreadableComponent(#[props(extends = GlobalAttributes)] attributes: Vec) -> Element {
rsx! {
div { class: "class1", style: "top:1;", ..attributes }
}
}
```

outputs this html with separated `class` and `style` attributes:

```

```

**Expected behavior**

it should output something like this:

```

```

**Environment:**

- Dioxus version: 0.6.3
- Rust version: 1.84.1
- OS info: Linux
- App platform: desktop

**Questionnaire**

I don't have time to fix this right now, but maybe later.