Cannot find TypeScript module with .js specifier in a TypeScript file

I'm not sure if this should be supported but it'd great to be able to import a TypeScript file with `.js` specifier in a TypeScript file, like so:

```ts
// module-a.ts
export const a = 100;

// main.ts
// import { a } from './module-a'; // it works without .js specifier
import { a } from './module-a.js'

console.debug(a); // 100
```