genType doesn't respect external-stdlib

[Hyeseong Kim]

Even when specified external-stdlib to @rescript/std in bsconfig.json. genType always import std from rescript instead of @rescript/std

Output.bs.js:

// Generated by ReScript, PLEASE EDIT WITH CARE

import * as Curry from "@rescript/std/lib/es6/curry.js";

Output.gen.ts:

/* TypeScript file generated from Vector.resi by genType. */
/* eslint-disable import/first */


// @ts-ignore: Implicit any on import
import * as Curry__Es6Import from 'rescript/lib/es6/curry.js';
const Curry: any = Curry__Es6Import;