Initial texture replacement implementation

Unmerged PR #5632, originally by @gdkchan

* Add mod manager support - @KeatonTheBot

* Remove redundant code - @KeatonTheBot

* Optimize, modernize code to newer C# standards where appropriate - @KeatonTheBot

Co-authored-by: KeatonTheBot <keaton@ryujinx.app>

src/Ryujinx.Common/Configuration/TextureFileFormat.cs

@@ -0,0 +1,12 @@
+using Ryujinx.Common.Utilities;
+using System.Text.Json.Serialization;
+
+namespace Ryujinx.Common.Configuration
+{
+    [JsonConverter(typeof(TypedStringEnumConverter<TextureFileFormat>))]
+    public enum TextureFileFormat
+    {
+        Dds,
+        Png,
+    }
+}