Implement codefix for adding missing await in return statements enclosed by try statements

[Andarist]

Given that async functions flatten returned promises it's a fairly easy mistake to make to assume that try/catch/finally enclosing a returned promise can handle that as if return await p would be written:

declare function mayThrow(): Promise<number>

async function caller(): Promise<number> {
  try {
    return mayThrow()
  } catch (err) {
    // oops, this *won't* be executed
  }
}

For that reason, I think, it would be great if TS could suggest adding that "missing" await

I'm opening this PR as a draft proposal for this feature. It still requires some work to be finalized but it already shows nicely the idea. I can finish this after receiving positive feedback.

I understand this is on the verge of being a lint rule so I'd be fine with closing this for that reason

[typescript-bot]

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

[Andarist]

not gonna lie, those messages could use some improvement

[Andarist]

TODO: recheck the desired behavior for async generators and add related tests

[Andarist]

This should actually produce this:

Suggested change

	return await (Math.random() > 0.5 ? inner() : 5);
	return Math.random() > 0.5 ? await inner() : 5;

The current implementation is a draft and it's not yet fully implemented for more complex cases. The problem with it is that for the code like this:

return Math.random() > 0.5 ? await inner1() : inner2();

the compiler shouldn't produce smth like this

return await (Math.random() > 0.5 ? await inner1() : inner2());

but rather:

return Math.random() > 0.5 ? await inner1() : await inner2();