How can we specify URL image scale in WebImage

The corresponding SwiftUI.AsyncImage snippets.

```swift
let scale = UIScreen.main.scale
let imageName = "\(baseURL)/\(name)_\(Int(scale))x.png"

return AsyncImage(
    url: URL(string: imageName),
    scale: scale
) { image in
    ...
} placeholder: {
    ...
}
```