Twig_Filter_Function() deprecated

[ywarnier]

The Twig_Filter_Function() is deprecated and should be replaced by either Twig_SimpleFilter() or Twig_SimpleFunction()

See https://scrutinizer-ci.com/g/chamilo/chamilo-lms/issues/1.11.x/files/main/gradebook/gradebook_view_result.php?selectedLabels%5B0%5D=11&orderField=issueCount&order=desc&honorSelectedPaths=0#inspectioncomment-40093232

[ywarnier]

@jmontoyaa I think you are the most suited for this task...
Also see https://www.sitepoint.com/extending-twig-templates-inheritance-filters-and-functions/ for a review of both new methods.