[ADD] News, Browse and Settings views ported to SwiftUI

This commit contains WIP SwiftUI versions of most of the views in SideStore.

AltStore/View Components/ObservableScrollView.swift

@@ -0,0 +1,47 @@
+//
+//  ObservableScrollView.swift
+//  SideStore
+//
+//  Created by Fabian Thies on 20.11.22.
+//  Copyright © 2022 Fabian Thies. All rights reserved.
+//
+
+import SwiftUI
+
+struct ObservableScrollView<Content: View>: View {
+    @Namespace var scrollViewNamespace
+    
+    @Binding var scrollOffset: CGFloat
+    
+    let content: (ScrollViewProxy) -> Content
+    
+    init(scrollOffset: Binding<CGFloat>, @ViewBuilder content: @escaping (ScrollViewProxy) -> Content) {
+        self._scrollOffset = scrollOffset
+        self.content = content
+    }
+    
+    var body: some View {
+        ScrollView {
+            ScrollViewReader { proxy in
+                content(proxy)
+                    .background(GeometryReader { geoReader in
+                        let offset = -geoReader.frame(in: .named(scrollViewNamespace)).minY
+                        Color.clear
+                            .preference(key: ScrollViewOffsetPreferenceKey.self, value: offset)
+                    })
+            }
+        }
+        .coordinateSpace(name: scrollViewNamespace)
+        .onPreferenceChange(ScrollViewOffsetPreferenceKey.self) { value in
+            scrollOffset = value
+        }
+    }
+}
+
+struct ScrollViewOffsetPreferenceKey: PreferenceKey {
+    static var defaultValue = CGFloat.zero
+    
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value += nextValue()
+    }
+}