Generated index.js file does not respect destDir build argument

[ikokostya]

Steps to reproduce:

1. Generate new project

   $ napi new @test/test
   

2. Specify destDir argument for napi build command:

   $ cd test
   $ napi build --platform build
   

3. Run tests

   npm run test
   

Result:

$ npm run test

> @test/test@0.0.0 test
> ava


  Uncaught exception in __test__/index.spec.mjs

  Error: Cannot find module '@test/test-linux-x64-gnu'
  Require stack:
  - /home/kostya/code/test/index.js

  › - index.js
  › Object.<anonymous> (index.js:174:31)

  ✖ __test__/index.spec.mjs exited with a non-zero exit code: 1
  ─

  1 uncaught exception

[TheLarkInn]

Agreed also running into this.

[TheLarkInn]

Opened #1481 to fix.