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/Systems/Configuration/ConfigurationState.Model.cs

@@ -11,6 +11,7 @@ using Ryujinx.Common.Helper;
 using Ryujinx.Common.Logging;
 using Ryujinx.Common.Utilities;
 using Ryujinx.HLE;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using RyuLogger = Ryujinx.Common.Logging.Logger;
@@ -689,6 +690,16 @@ namespace Ryujinx.Ava.Systems.Configuration
                     : ldnServer;
             }
 
+            public string GetLdnWebServer()
+            {
+                if (Environment.GetEnvironmentVariable("RYULDN_WEB_HOST") is not { } ldnWebServer)
+                    ldnWebServer = LdnServer;
+
+                return string.IsNullOrEmpty(ldnWebServer)
+                    ? SharedConstants.DefaultLanPlayWebHost
+                    : ldnWebServer;
+            }
+
             public MultiplayerSection()
             {
                 LanInterfaceId = new ReactiveObject<string>();