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

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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`](https://tsdoc.org/pages/tags/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.

Inizia individuando la gestione esistente delle annotazioni @deprecated e la ricerca nella gerarchia delle classi menzionata nell’issue. Determina come viene rappresentato @sealed e dove vengono prodotti i riscontri relativi all’override o all’ereditarietà; il lavoro è completato quando una sottoclasse che esegue l’override di un metodo sealed o eredita da una superclasse sealed riceve una diagnosi o un indicatore visibile.

Scritto dal modello di indicizzazione a partire dal testo della issue.