feat: Implement new sign in flow

lib/widgets/view_model_builder.dart

@@ -0,0 +1,43 @@
+import 'package:flutter/material.dart';
+
+class ViewModelBuilder<T extends ValueNotifier> extends StatefulWidget {
+  final T Function() create;
+  final Widget Function(BuildContext context, T viewModel, Widget? child)
+  builder;
+  final Widget? child;
+  const ViewModelBuilder({
+    super.key,
+    required this.create,
+    required this.builder,
+    this.child,
+  });
+
+  @override
+  State<ViewModelBuilder<T>> createState() => _ViewModelBuilderState<T>();
+}
+
+class _ViewModelBuilderState<T extends ValueNotifier>
+    extends State<ViewModelBuilder<T>> {
+  late final T _viewModel;
+
+  @override
+  void initState() {
+    _viewModel = widget.create();
+    super.initState();
+  }
+
+  @override
+  void dispose() {
+    _viewModel.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return ValueListenableBuilder(
+      valueListenable: _viewModel,
+      builder: (context, value, child) =>
+          widget.builder.call(context, _viewModel, child),
+    );
+  }
+}