[ADD] Authentication view for connecting SideStore to an Apple ID

AltStore/View Components/RoundedTextField.swift

@@ -0,0 +1,52 @@
+//
+//  RoundedTextField.swift
+//  SideStore
+//
+//  Created by Fabian Thies on 29.11.22.
+//  Copyright © 2022 SideStore. All rights reserved.
+//
+
+import SwiftUI
+
+struct RoundedTextField: View {
+    
+    let title: String?
+    let placeholder: String
+    @Binding var text: String
+    let isSecure: Bool
+    
+    init(title: String?, placeholder: String, text: Binding<String>, isSecure: Bool = false) {
+        self.title = title
+        self.placeholder = placeholder
+        self._text = text
+        self.isSecure = isSecure
+    }
+    
+    init(_ placeholder: String, text: Binding<String>, isSecure: Bool = false) {
+        self.init(title: nil, placeholder: placeholder, text: text, isSecure: isSecure)
+    }
+    
+    var body: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            if let title {
+                Text(title.uppercased())
+                    .font(.system(size: 12))
+                    .foregroundColor(.secondary)
+                    .padding(.horizontal)
+            }
+            
+            HStack(alignment: .center) {
+                if isSecure {
+                    SecureField(placeholder, text: $text)
+                } else {
+                    TextField(placeholder, text: $text)
+                }
+            }
+            .padding()
+            .background(
+                RoundedRectangle(cornerRadius: 12)
+                    .foregroundColor(Color(.secondarySystemBackground))
+            )
+        }
+    }
+}