Use index fragment shader output when dual source blend is enabled (#4404)

* Use index fragment shader output when dual source blend is enabled

* Shader cache version bump

* Actually set DualSourceBlendEnabled to true

* Fix XML doc

---------

Co-authored-by: Ac_K <Acoustik666@gmail.com>

Ryujinx.Graphics.Gpu/Shader/ShaderSpecializationState.cs

@@ -535,6 +535,11 @@ namespace Ryujinx.Graphics.Gpu.Shader
                 return false;
             }
 
+            if (graphicsState.DualSourceBlendEnable != GraphicsState.DualSourceBlendEnable)
+            {
+                return false;
+            }
+
             return Matches(channel, ref poolState, checkTextures, isCompute: false);
         }