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.cpp

@@ -62,6 +62,8 @@ std::string_view GetTextureFilterName(TextureFilter filter) {
         return "ScaleForce";
     case TextureFilter::xBRZ:
         return "xBRZ";
+    case TextureFilter::MMPX:
+        return "MMPX";
     default:
         return "Invalid";
     }