Add lint rule to enforce @sealed

[DayKev]

Similar to noPrivateImports for the @public/etc JSDoc/TSDoc tags, a rule enforcing subclasses don't override methods marked as @sealed would be nice to have. I tried searching for an equivalent ESLint rule but there doesn't appear to be one (or at least it's not easy to find).
Unfortunately the TS team has repeatedly rejected adding a sealed/final/whatever keyword, and in fact explicitly said someone should just make a lint rule if they want it, so this is the only choice to get this behavior.
Since @sealed already exists as part of the TSDoc spec, I think it's a good choice to use as the thing to check for.

A simplified example:

class SomeClass {
  /** @sealed */
  public doThing() {
    this.onDoThingStart();
    // ... impl ...
    this.onDoThingEnd();
  }

  /** Override this as needed */
  protected onDoThingStart() {}
  /** Override this as needed */
  protected onDoThingEnd() {}
}

class MyClass extends SomeClass {
  public override doThing() { // <-- lint error (regardless of the existence of the `override` keyword)
    // ...
  }

  protected override onDoThingEnd() {
    // do some stuff
  }
}

If possible it would be good to support mixins too, though at least for us we have very few mixins so if the added complexity would delay the rule I have no problem with it not being supported initially.

function MixinClass<CBase extends AbstractConstructor<SomeClass>>(Base: CBase) {
  abstract class Thing extends Base {
    // ...

    /** @sealed */
    protected doStuff() { /* ... */ }

    // ...
  }

  return Thing as AbstractConstructor<Thing> & CBase;
}

export abstract class AClass extends MixinClass(SpecificClass) { /* ... */ }