`isolatedDeclarations` quick-fix cannot consistently use auto-imports

// @module: preserve
// @isolatedDeclarations: true

// @Filename: types.ts
export type Thing = {};

// @Filename: funcs.ts
import type { Thing } from "./types";

export function makeThing(): Thing {
    throw {};
}

// @Filename: exporter.ts
import { makeThing } from "./funcs";

export let thing = makeThing();

The test has isolatedDeclarations set to true, so export let thing needs an annotation.

Ordinarily, we have a best-effort import adder for Thing which works if Thing is available through an existing import; but because exporter.ts doesn't import types.ts, it doesn't work in this case.