Adds an `overlay` to a `View` that aligns the middle of the overlay with the edge of the parent, like a badge.

View+badge.swift

extension View {
    func badge<Badge: View>(_ badge: Badge, alignment: Alignment = .topTrailing) -> some View {
        overlay(
            badge
                .alignmentGuide(.leading, computeValue: splitDimension(\.width))
                .alignmentGuide(HorizontalAlignment.center, computeValue: splitDimension(\.width))
                .alignmentGuide(.trailing, computeValue: splitDimension(\.width))
                .alignmentGuide(.top, computeValue: splitDimension(\.height))
                .alignmentGuide(VerticalAlignment.center, computeValue: splitDimension(\.height))
                .alignmentGuide(.bottom, computeValue: splitDimension(\.height)),
            alignment: alignment
        )
    }
    private func splitDimension(_ axis: KeyPath<ViewDimensions, CGFloat>) -> (ViewDimensions) -> CGFloat {
        { $0[keyPath: axis] / 2 }
    }
}