Add unimplemented warnings

Layout needs to be expanded to compute these layout guides.
safeArea in particular will require a bottom to top recursion of overlapping Rects and will need a cache, which requires major refactoring.
margin is much simpler but it would be beneficial to implement both at the same time.

Author: STREGA

Sources/GateEngine/UI/View.swift

@@ -231,9 +231,11 @@ open class View {
     }
 
     public var marginInsets: Insets = .zero
+    @available(*, deprecated, message: "margin guide not implemented. Will crash if used.")
     public private(set) lazy var margin: Layout.Guide = Layout.Guide(view: self)
 
     public var additionalSafeAreaInsets: Insets = .zero
+    @available(*, deprecated, message: "safeArea guide not implemented. Will crash if used.")
     public private(set) lazy var safeArea: Layout.Guide = Layout.Guide(view: self)
 
     internal lazy var layoutGuide: Layout.Guide = Layout.Guide(view: self)