Improve VVC Support

Core/RenderManager.cs

@@ -444,6 +444,10 @@ namespace ADOFAIRenderer.Core
             {
                 ext = ".webm";
             }
+            else if (selectedCodec == Codec.VVC)
+            {
+                ext = ".mkv";
+            }
 
             var startTime = DateTime.Now;
             var fileName = startTime.ToString("yyyy-MM-dd HH-mm-ss") + ext;