Add support for SwiftUI custom shapes

[marcprux]

Discussed in https://github.com/skiptools/skip/discussions/31

^{Originally posted by **shial4** November 3, 2023} Please add support for SwiftUI Shape I would love to be able to make this lib SKIP enabled https://github.com/shial4/SwiftUIComponents/blob/main/Sources/SwiftUIComponents/Components/Shapes/Chevron.swift ``` /// A shape representing a chevron. public struct Chevron: Shape { /// The thickness of the chevron as a fraction of the minimum dimension of the containing rect. public let thickness: Double /// Creates a chevron shape with the specified thickness. /// - Parameter thickness: The thickness of the chevron as a fraction of the minimum dimension of the containing rect. Default value is 0.25. public init(thickness: Double = 0.25) { self.thickness = thickness } public func path(in rect: CGRect) -> Path { let offset: Double = min(rect.size.width, rect.size.height) * thickness return Path { path in path.move(to: CGPoint(x: rect.minX, y: rect.minY)) path.addLine(to: CGPoint(x: rect.maxX, y: rect.midY)) path.addLine(to: CGPoint(x: rect.minX, y: rect.maxY)) path.addLine(to: CGPoint(x: rect.minX - offset, y: rect.maxY)) path.addLine(to: CGPoint(x: rect.maxX - offset, y: rect.midY)) path.addLine(to: CGPoint(x: rect.minX - offset, y: rect.minY)) path.closeSubpath() } } } struct Chevron_Previews: PreviewProvider { static var previews: some View { VStack { HStack { Chevron().stroke(Color.white) Chevron().fill(Color.white) }.frame(width: 32, height: 64) } } } ``` including path transform such as ``` .applying(CGAffineTransform(scaleX: 1, y: -1)) .applying(CGAffineTransform(translationX: 0, y: rect.size.height)) ```

[aabewhite]

Added in 0.3.15. Please let us know if you run into any issues with it!