Make Sanitizer obey rules from config.yml

[bobdenotter]

No description provided.

[I-Valchev]

Issue with implementing this:

The Sanitiser gets instantiated within the getTwigValue() method of the Field entity, meaning that the $config cannot be autowired to an entity. Also, the $config cannot be passed from the Content class, because by the time getTwigValue() is called in Twig ({{ field.twigValue() }}), the Content is no longer accessible.

The problem is how to pass the config to the getTwigValue() method, which will instantiate the Sanitiser with it.