Add Appearance to the catalog

Author: colemancda

Demo/App.swiftpm/Sources/Catalog.swift

@@ -41,6 +41,7 @@ struct CatalogEntry: Identifiable {
         CatalogEntry(id: "grid", title: "Grid", screen: AnyCatalogScreen(GridPlayground())),
         CatalogEntry(id: "form", title: "Form", screen: AnyCatalogScreen(FormPlayground())),
         CatalogEntry(id: "modifier", title: "Modifiers", screen: AnyCatalogScreen(ModifierPlayground())),
+        CatalogEntry(id: "appearance", title: "Appearance", screen: AnyCatalogScreen(AppearancePlayground())),
         CatalogEntry(id: "interaction", title: "Interaction", screen: AnyCatalogScreen(InteractionPlayground())),
         CatalogEntry(id: "navigation", title: "Navigation", screen: AnyCatalogScreen(NavigationPlayground())),
         CatalogEntry(id: "tab", title: "TabView", screen: AnyCatalogScreen(TabViewPlayground())),