Support .d.ts

* Parse .d.ts and create alias for them
  - https://deno.land/std/manual.md

## Patterns

* Compiler hint

```ts
// @deno-types="./vendor/https/deno.land/std/foo/bar.d.ts"
import * as bar from "./bar.js";
```

* Triple-slash reference in `.js`

```ts
/// <reference types="./vendor/https/deno.land/std/foo/bar.d.ts" />
export const bar = "bar";
```