VertexLoaderBase: Allow the vertex loader type to be set via config

Source/Core/VideoCommon/VideoConfig.cpp

@@ -206,6 +206,8 @@ void VideoConfig::Refresh()
   bGraphicMods = Config::Get(Config::GFX_MODS_ENABLE);
 
   customDriverLibraryName = Config::Get(Config::GFX_DRIVER_LIB_NAME);
+
+  vertex_loader_type = Config::Get(Config::GFX_VERTEX_LOADER_TYPE);
 }
 
 void VideoConfig::VerifyValidity()