[Bridge][Twig] Replace deprecated features

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This PR replaces the deprecated classes `Twig_Function_Node` and `Twig_Function_Method` by the`Twig_SimpleFunction`.

I'm not sure if it is the right way to go, so let me know if something needs to be updated.