Support target/module tsconfig settings via directive

[danvk]

I'd like to use top-level await in a code sample:

export async function fetchPeak(peakId: string): Promise<MountainPeak>;
export async function fetchPeak(peakId: string): Promise<unknown> {
  return checkedFetchJSON(`/api/mountain-peaks/${peakId}`);  // OK
}

const denali = await fetchPeak('denali');
//    ^? const denali: MountainPeak

If I do so, I get the following error:

hide-unsafe-casts.asciidoc:134:16-21: Unexpected TypeScript error: Top-level 'await' expressions are only allowed when the 'module' option is set to 'es2022', 'esnext', 'system', 'node16', or 'nodenext', and the 'target' option is set to 'es2017' or higher.

Adding these directives does not fix the error:

// verifier:tsconfig:module=es2022
// verifier:tsconfig:target=es2017

It would be nice if this worked!