New feature: twig extension - html_title_raw

It appears that the patch in #4 is only compatible with Drupal 8 and 9, because starting in Drupal 10.0.0, Twig was updated from 2.x to 3.x → ; and in Twig 3.x, the root-namespaed \Twig_Extension and \Twig_SimpleFilter classes were removed in favour of \Twig\Extension\AbstractExtension and \Twig\TwigFilter respectively (the root-namespaced classes had been deprecated in Twig 2.x but not removed).

Note this will drop support for Drupal 8, which used Twig 1.x → , so I've updated the html_title.info.yml file at the same time.

Here's a patch that should be compatible with Drupal 9 and 10. (note that @burnellw_cit filed 🐛 Twig_Extension non-existent Closed: duplicate to fix this issue for Drupal 10).

Putting this into needs review so Testbot will run; then I'll put it back to Needs work because:

1. it needs tests as per #3
2. it needs hardening as per #5
3. it needs documentation as per #5