Doesn't respect compiler hints

[Liamolucko]

At the moment, deno doc doesn't respect /// <reference types="..." /> nor X-TypeScript-Types.

Example:

foo.js

/// <reference types="./foo.d.ts" />
export const foo = "foo";

foo.d.ts

export const foo: string;

Expected output of deno doc foo.js:

const foo: string

Actual:

const foo

[Liamolucko]

I'm not sure if this is an issue with deno_doc or the Deno CLI, actually.

[Liamolucko]

Since these compiler hints are Deno-specific, and this crate is meant to be more generic, moved to denoland/deno#8450.