feature: UI: LDN Games Viewer

This window can be accessed via "Help" menu in the title bar.
This menu's data is synced with the in-app-list LDN game data, and that has been modified to hide unjoinable games (in-progress and/or private (needing a passphrase)). You can still see these games in the list.

src/Ryujinx/UI/Views/Main/MainMenuBarView.axaml.cs

@@ -49,6 +49,7 @@ namespace Ryujinx.Ava.UI.Views.Main
             XciTrimmerMenuItem.Command = Commands.Create(XciTrimmerView.Show);
             AboutWindowMenuItem.Command = Commands.Create(AboutView.Show);
             CompatibilityListMenuItem.Command = Commands.Create(() => CompatibilityListWindow.Show());
+            LdnGameListMenuItem.Command = Commands.Create(() => LdnGamesListWindow.Show());
 
             UpdateMenuItem.Command = MainWindowViewModel.UpdateCommand;