[Typescript] Give a visual indicator when overriding methods with the `@sealed` js/tsdoc annotation

I notice that vscode has builtin support for reading the @deprecated jsdoc / tsdoc annotation that can appear on methods and variables, which causes them to appear with a strikethrough.

It would be useful if there was a similar visual indicator when a subclass attempts to override a method that is marked as @sealed in its superclass, or when it tries to inherit from a sealed superclass. (not a strikethrough, but perhaps squiggles, or any kind of feedback).

Given that there is already machinery that looks through the class hierarchy to determine that a field defined in a parent class is marked as deprecated, I would presume it wouldn't be that difficult to also identify the @sealed annotation.

Commencez par localiser la gestion existante des annotations @deprecated et la recherche dans la hiérarchie de classes mentionnée dans l’issue. Déterminez comment @sealed est représenté et où les retours concernant la surcharge ou l’héritage sont produits ; le travail est terminé lorsqu’une sous-classe qui surcharge une méthode scellée ou hérite d’une superclasse scellée reçoit un diagnostic ou un indicateur visible.