video_core: Add MMPX texture filter (#6564)

* video_core: Add MMPX texture shader

* mmpx: Apply mix to mask alpha edge artifacting

* mmpx: Do not use deprecated texture fuction.

src/common/settings.h

@@ -74,6 +74,7 @@ enum class TextureFilter : u32 {
     NearestNeighbor = 3,
     ScaleForce = 4,
     xBRZ = 5,
+    MMPX = 6
 };
 
 namespace NativeButton {