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

还没有人认领这个 Issue。

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.

首先定位现有的 @deprecated 注解处理逻辑，以及 issue 中提到的类层次结构查找逻辑。确定 @sealed 是如何表示的，以及 override 或继承反馈在哪里生成；当一个 override sealed 方法的子类，或从 sealed 超类继承的子类，能够收到可见的诊断信息或指示器时，即表示完成。

由索引模型根据 Issue 内容生成。