Initial work on a setup wizard

Setup wizard abstraction & architecture from TKMM

src/Ryujinx/Systems/SetupWizard/SetupWizardPage.cs

@@ -0,0 +1,62 @@
+using Avalonia.Controls.Presenters;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using Ryujinx.Ava.Common.Locale;
+using Ryujinx.Ava.UI.ViewModels;
+using Ryujinx.Systems.SetupWizard;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Ryujinx.Ava.Systems.SetupWizard
+{
+    public partial class SetupWizardPage(bool isFirstPage = false) : BaseModel
+    {
+        protected bool? _result;
+        protected readonly CancellationTokenSource _cancellationTokenSource = new();
+    
+        public bool IsFirstPage { get; } = isFirstPage;
+
+        [ObservableProperty]
+        private string? _title;
+
+        [ObservableProperty]
+        private object? _content;
+
+        [ObservableProperty]
+        private object? _helpContent;
+
+        [ObservableProperty] 
+        private object? _actionContent = LocaleManager.Instance[LocaleKeys.SetupWizardActionNext];
+
+        [RelayCommand]
+        private void MoveBack()
+        {
+            _result = false;
+            _cancellationTokenSource.Cancel();
+        }
+
+        [RelayCommand]
+        private void MoveNext()
+        {
+            _result = true;
+            _cancellationTokenSource.Cancel();
+        }
+
+        public async ValueTask<bool> Show(ContentPresenter presenter)
+        {
+            presenter.Content = new SetupWizardPageView 
+            {
+                DataContext = this,
+            };
+
+            try {
+                await Task.Delay(-1, _cancellationTokenSource.Token);
+            }
+            catch (TaskCanceledException) {
+                return _result ?? false;
+            }
+
+            return false;
+        }
+    }
+}