Allow return type annotations on setters

Nobody has claimed this yet.

Setters can return values, so TypeScript should support declaring return types on setters.

### 🔎 Search Terms

setter return type

### 🕗 Version & Regression Information

This is the behavior in every version I tried, and I reviewed the FAQ for relevant entries

### ⏯ Playground Link

- Without return type: https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAZiEMC8MDeAoGMIFNYBGAhgE4AUA+gJTpbYwn4CuJYMA5I1C2wG5EAbJrnYBuOgF8ME8aEiw8UKLhIQAwkTAAlZqwBqg4RBQwA8gQBWuYFAB0Ac3ymA7mAAKJEAAcVUAJ4AIrgQwCQAll5QIOQIIAA0HMQk7FS2imQ0yFkcXDww-EIisuAQIAK4tgIg9mQABorKqjDAmgAkaA0q6po63PqGwQD8HOwwAFwwAETsUJMSDLp8AxC1VKJAA
- With return type: https://www.typescriptlang.org/play/?#code/MYewdgzgLgBAZiEMC8MDeAoGMIFNYBGAhgE4AUA+gJQBcOUJAlmAObpbYwn4CuJYMAOTcofAQDciAGx65BAbg4BfDEsWhIsPFCi4SEAMJEwAJV78AatNkQUMAPIEAVrmBQAdC3z2A7mAAKJCAADnpQAJ4AIrgQwEzBUCDkCCAANELEJIJU7tpkVCjIqMLmEtZy6uAQIFK47lIgLGQABtq6+jDAxgAkaG16hsZmopblEAD8QoIwdABEglCzSlylMJIyMc1U8kA

### 💻 Code

```ts
const foo = {
set bar(_) {
return 'return value';
}
};
const settersCanReturnValues = Object.getOwnPropertyDescriptor(foo, 'bar').set() === 'return value';
console.log(`setters can${settersCanReturnValues? '' : "'t"} return values`);
```

Same code, with an explicit return type:

```ts
const foo = {
set bar(_): string {
return 'return value';
}
};
const settersCanReturnValues = Object.getOwnPropertyDescriptor(foo, 'bar').set() === 'return value';
console.log(`setters can${settersCanReturnValues? '' : "'t"} return values`);
```

### 🙁 Actual behavior

TypeScript compiler emits invalid JavaScript containing return type declaration syntax.

### 🙂 Expected behavior

TypeScript compiler supports and removes return type declarations from setters.

### Additional information about the issue

Start with the two TypeScript Playground examples and compare the emitted JavaScript for setters with and without an explicit return type. The change is done when the annotated setter compiles to valid JavaScript with its return type removed, while the existing unannotated example continues to work; add a regression test in the compiler's existing test suite.

Written by the indexing model from the issue text.