Feature: Contextual package.json exports generation

[cawfeecoder]

Description

This adds the ability for exports to contextually determine whether index.{js,ts,tsx,jsx} is located at the top level (i.e. src/index.) or within a sub-folder (i.e. src/button/index.) to determine what the appropriate named export should be.

In the case of a sub-folder, the export becomes "./${sub_folder}" instead of "./index" (old behavior).

This resolves #3

[UpperCod]

Thanks for the feature, @atomico/exports was created to keep a name pattern from the file name, example:

src
  |- component-1
  |  |- component-1.jsx
  |  |- component-1.test.js
  |  |- component-1.css
  |- component-2
  |  |- component-2.jsx
  |  |- component-2.test.js
  |  |- component-2.css

npx exports src/*/*.{js,jsx,ts,tsx} --main component-1 --exports

{
  "exports": {
    ".": "dist/component-1.js",
    "component-2": "dist/component-2.js"
  }
}

It is a pattern that inherits from the Stencil development model, but I think we can add it as requested, for this we must consider the following:

1. the subfolder is only conditional on the use of index.js
2. there can be more than one export from the folder

it could be something like this:

const parsedPath = path.parse(output);
const { name } = {
  name:
    parsedPath.name === "index"
      ? path.parse(parsedPath.dir).name
      : parsedPath.name,
};

when detecting the use of index as a name it moves to the sub-folder