This PR removes an unneeded anonymous lifetime from the `cx` parameter
to `Render::render`.

This makes it so the anonymous lifetime doesn't show up when
implementing the `Render` trait via a code action:

#### Before

```rs
struct Foo;

impl Render for Foo {
    fn render(&mut self, window: &mut Window, cx: &mut Context<'_, Self>) -> impl IntoElement {
        todo!()
    }
}
```

#### After

```rs
struct Foo;

impl Render for Foo {
    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        todo!()
    }
}
```

Release Notes:

- N/A