Implement EFB copy filter and gamma in hardware backends

Also makes y_scale a dynamic parameter for EFB copies, as it doesn't
make sense to keep it as part of the uid, otherwise we're generating
redundant shaders.

Source/Core/Core/ConfigLoaders/IsSettingSaveable.cpp

@@ -85,6 +85,7 @@ bool IsSettingSaveable(const Config::ConfigLocation& config_location)
       Config::GFX_ENHANCE_MAX_ANISOTROPY.location,
       Config::GFX_ENHANCE_POST_SHADER.location,
       Config::GFX_ENHANCE_FORCE_TRUE_COLOR.location,
+      Config::GFX_ENHANCE_DISABLE_COPY_FILTER.location,
 
       // Graphics.Stereoscopy