[ADD] Hint for new users who don't have any sources

AltStore/View Components/HintView.swift

@@ -0,0 +1,42 @@
+//
+//  HintView.swift
+//  SideStore
+//
+//  Created by Fabian Thies on 15.01.23.
+//  Copyright © 2023 SideStore. All rights reserved.
+//
+
+import SwiftUI
+
+struct HintView<Content: View>: View {
+
+    var backgroundColor: Color = Color(.tertiarySystemBackground)
+
+    @ViewBuilder
+    let content: () -> Content
+    
+    var body: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            self.content()
+        }
+        .padding()
+        .background(self.backgroundColor)
+        .clipShape(RoundedRectangle(cornerRadius: 8))
+    }
+}
+
+struct HintView_Previews: PreviewProvider {
+    static var previews: some View {
+        ZStack {
+            Color(.secondarySystemBackground).edgesIgnoringSafeArea(.all)
+
+            HintView {
+                Text("Hint Title")
+                    .bold()
+
+                Text("This hint view can be used to tell the user something about how SideStore works.")
+                    .foregroundColor(.secondary)
+            }
+        }
+    }
+}