How to make simple HUD in SwiftUI

Issue #723

Use @ViewBuilder to build dynamic content for our HUD. For blur effect, here I use NSVisualEffectView, but we can use .blur modifier also

struct HUD<Content>: View where Content: View {
    let content: () -> Content

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content
    }

    var body: some View {
        content()
        .frame(width: 80, height: 80)
        .background(
            VisualEffectView(material: .hudWindow)
                .clipShape(RoundedRectangle(cornerRadius: 12))
                .shadow(color: Color.black.opacity(0.22), radius: 12, x: 0, y: 5)
        )
    }
}

Then we can make some wrappers for information and progress HUD

struct HUD<Content>: View where Content: View {
    let content: () -> Content

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content
    }

    var body: some View {
        content()
        .frame(width: 80, height: 80)
        .background(
            VisualEffectView()
        )
        .cornerRadius(10)
        .shadow(color: Color.gray.opacity(0.3), radius: 1, x: 0, y: 1)
    }
}